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Commit 864c4703 authored by Ben Avison's avatar Ben Avison
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Added required documentation for release of source code from IJG.

parent 72e3ff6f
master MigrateIJG8b SprExtend-1_85 SprExtend-1_84 SprExtend-1_83 SprExtend-1_82 SprExtend-1_81 SprExtend-1_80 SprExtend-1_79 SprExtend-1_78 SprExtend-1_77 SprExtend-1_76 SprExtend-1_75 SprExtend-1_74 SprExtend-1_73 SprExtend-1_72 SprExtend-1_71 SprExtend-1_71-nocfsi SprExtend-1_70 SprExtend-1_70-tracef SprExtend-1_70-headers SprExtend-1_69 SprExtend-1_68 SprExtend-1_67 SprExtend-1_66 SprExtend-1_65 SprExtend-1_64 SprExtend-1_63 SprExtend-1_62 SprExtend-1_61 SprExtend-1_60 SprExtend-1_59 SprExtend-1_58 SprExtend-1_57 SprExtend-1_56 SprExtend-1_55 SprExtend-1_54 SprExtend-1_53 SprExtend-1_52 SprExtend-1_51 SprExtend-1_50 SprExtend-1_49 SprExtend-1_48 SprExtend-1_47 SprExtend-1_46 SprExtend-1_45 SprExtend-1_44 SprExtend-1_43 SprExtend-1_42 SprExtend-1_41 SprExtend-1_40 SprExtend-1_39 SprExtend-1_38 SprExtend-1_38-1_35_2_16 SprExtend-1_38-1_35_2_15 SprExtend-1_38-1_35_2_14 SprExtend-1_38-1_35_2_13 SprExtend-1_38-1_35_2_12 SprExtend-1_38-1_35_2_11 SprExtend-1_38-1_35_2_10 SprExtend-1_38-1_35_2_9 SprExtend-1_38-1_35_2_8 SprExtend-1_38-1_35_2_7 SprExtend-1_38-1_35_2_6 SprExtend-1_38-1_35_2_5 SprExtend-1_38-1_35_2_4 SprExtend-1_38-1_35_2_3 SprExtend-1_38-1_35_2_2 SprExtend-1_38-1_35_2_1 SprExtend-1_37 SprExtend-1_36 SprExtend-1_35 SprExtend-1_34 SprExtend-1_33 SprExtend-1_32 SprExtend-1_31 SprExtend-1_30 SprExtend-1_29 SprExtend-1_28 SprExtend-1_27 SprExtend-1_26 SprExtend-1_25 SprExtend-1_24 SprExtend-1_23 SprExtend-1_22 SprExtend-1_21 SprExtend-1_20 SprExtend-1_19 SprExtend-1_18
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Some of the accompanying sources were based upon software from the
Independent JPEG Group, specifically from releases 3, 4 and 5. In accordance
with the terms of redistribution of that source code, see below the diffs
from the appropriate release to the earliest revision of each relevant
source code file in CVS, and see also the matching README file that you
should have received alongside this one. CVS may be used to derive the diffs
to other revisions.
BJGA, 2007-10-18
diff -U 3 -H -b -B -d -p -r -N -- jpeg-3/jconfig.h cvs/h/jconfig
--- jpeg-3/jconfig.h 1992-03-08 03:26:04.000000000 +0000
+++ cvs/h/jconfig 1996-11-05 09:45:08.000000000 +0000
@@ -1,3 +1,20 @@
+/* This source code in this file is licensed to You by Castle Technology
+ * Limited ("Castle") and its licensors on contractual terms and conditions
+ * ("Licence") which entitle you freely to modify and/or to distribute this
+ * source code subject to Your compliance with the terms of the Licence.
+ *
+ * This source code has been made available to You without any warranties
+ * whatsoever. Consequently, Your use, modification and distribution of this
+ * source code is entirely at Your own risk and neither Castle, its licensors
+ * nor any other person who has contributed to this source code shall be
+ * liable to You for any loss or damage which You may suffer as a result of
+ * Your use, modification or distribution of this source code.
+ *
+ * Full details of Your rights and obligations are set out in the Licence.
+ * You should have received a copy of the Licence with this source code file.
+ * If You have not received a copy, the text of the Licence is available
+ * online at www.castle-technology.co.uk/riscosbaselicence.htm
+ */
/*
* jconfig.h
*
@@ -5,27 +22,7 @@
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
- * This file contains preprocessor declarations that help customize
- * the JPEG software for a particular application, machine, or compiler.
- * Edit these declarations as needed (or add -D flags to the Makefile).
- */
-
-
-/*
- * These symbols indicate the properties of your machine or compiler.
- * The conditional definitions given may do the right thing already,
- * but you'd best look them over closely, especially if your compiler
- * does not handle full ANSI C. An ANSI-compliant C compiler should
- * provide all the necessary features; __STDC__ is supposed to be
- * predefined by such compilers.
- */
-
-/*
- * HAVE_STDC is tested below to see whether ANSI features are available.
- * We avoid testing __STDC__ directly for arcane reasons of portability.
- * (On some compilers, __STDC__ is only defined if a switch is given,
- * but the switch also disables machine-specific features we need to get at.
- * In that case, -DHAVE_STDC in the Makefile is a convenient solution.)
+ * Seriously updated for use deep within RISC OS.
*/
#ifdef __STDC__ /* if compiler claims to be ANSI, believe it */
@@ -52,153 +48,18 @@
#define HAVE_UNSIGNED_SHORT
#endif
-/* Define this if an ordinary "char" type is unsigned.
- * If you're not sure, leaving it undefined will work at some cost in speed.
- * If you defined HAVE_UNSIGNED_CHAR then it doesn't matter very much.
- */
-
-/* #define CHAR_IS_UNSIGNED */
-
-/* Define this if your compiler implements ">>" on signed values as a logical
- * (unsigned) shift; leave it undefined if ">>" is a signed (arithmetic) shift,
- * which is the normal and rational definition.
- */
-
-/* #define RIGHT_SHIFT_IS_UNSIGNED */
-
-/* Define "void" as "char" if your compiler doesn't know about type void.
- * NOTE: be sure to define void such that "void *" represents the most general
- * pointer type, e.g., that returned by malloc().
- */
-
-/* #define void char */
-
-/* Define const as empty if your compiler doesn't know the "const" keyword. */
-/* (Even if it does, defining const as empty won't break anything.) */
-
-#ifndef HAVE_STDC /* ANSI C and C++ compilers should know it. */
-#ifndef __cplusplus
-#define const
-#endif
-#endif
-
-/* For 80x86 machines, you need to define NEED_FAR_POINTERS,
- * unless you are using a large-data memory model or 80386 flat-memory mode.
- * On less brain-damaged CPUs this symbol must not be defined.
- * (Defining this symbol causes large data structures to be referenced through
- * "far" pointers and to be allocated with a special version of malloc.)
- */
-
-#ifdef MSDOS
-#define NEED_FAR_POINTERS
-#endif
-
-
-/* The next three symbols only affect the system-dependent user interface
- * modules (jcmain.c, jdmain.c). You can ignore these if you are supplying
- * your own user interface code.
- */
-
-/* Define this if you want to name both input and output files on the command
- * line, rather than using stdout and optionally stdin. You MUST do this if
- * your system can't cope with binary I/O to stdin/stdout. See comments at
- * head of jcmain.c or jdmain.c.
- */
-
-#ifdef MSDOS /* two-file style is needed for PCs */
-#define TWO_FILE_COMMANDLINE
-#endif
-#ifdef THINK_C /* needed for Macintosh too */
-#define TWO_FILE_COMMANDLINE
-#endif
-
-/* Define this if your system needs explicit cleanup of temporary files.
- * This is crucial under MS-DOS, where the temporary "files" may be areas
- * of extended memory; on most other systems it's not as important.
- */
-
-#ifdef MSDOS
-#define NEED_SIGNAL_CATCHER
-#endif
-
-/* By default, we open image files with fopen(...,"rb") or fopen(...,"wb").
- * This is necessary on systems that distinguish text files from binary files,
- * and is harmless on most systems that don't. If you have one of the rare
- * systems that complains about the "b" spec, define this symbol.
- */
-
-/* #define DONT_USE_B_MODE */
-
-
-/* If you're getting bored, that's the end of the symbols you HAVE to
- * worry about. Go fix the makefile and compile.
- */
-
-
-/* On a few systems, type boolean and/or macros FALSE, TRUE may appear
- * in standard header files. Or you may have conflicts with application-
- * specific header files that you want to include together with these files.
- * In that case you need only comment out these definitions.
- */
-
typedef int boolean;
+#ifndef BOOL
+ #define BOOL int
+#endif
#undef FALSE /* in case these macros already exist */
#undef TRUE
#define FALSE 0 /* values of boolean */
#define TRUE 1
-/* This defines the size of the I/O buffers for entropy compression
- * and decompression; you could reduce it if memory is tight.
- */
-
-#define JPEG_BUF_SIZE 4096 /* bytes */
-
-
-
/* These symbols determine the JPEG functionality supported. */
-/*
- * These defines indicate whether to include various optional functions.
- * Undefining some of these symbols will produce a smaller but less capable
- * program file. Note that you can leave certain source files out of the
- * compilation/linking process if you've #undef'd the corresponding symbols.
- * (You may HAVE to do that if your compiler doesn't like null source files.)
- */
-
-/* Arithmetic coding is unsupported for legal reasons. Complaints to IBM. */
-#undef ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
-#define MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
-#define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
-#define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing during decoding? */
-#define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */
-#define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */
-/* these defines indicate which JPEG file formats are allowed */
#define JFIF_SUPPORTED /* JFIF or "raw JPEG" files */
-#undef JTIFF_SUPPORTED /* JPEG-in-TIFF (not yet implemented) */
-/* these defines indicate which image (non-JPEG) file formats are allowed */
-#define GIF_SUPPORTED /* GIF image file format */
-/* #define RLE_SUPPORTED */ /* RLE image file format (by default, no) */
-#define PPM_SUPPORTED /* PPM/PGM image file format */
-#define TARGA_SUPPORTED /* Targa image file format */
-#undef TIFF_SUPPORTED /* TIFF image file format (not yet impl.) */
-
-/* more capability options later, no doubt */
-
-
-/*
- * Define exactly one of these three symbols to indicate whether you want
- * 8-bit, 12-bit, or 16-bit sample (pixel component) values. 8-bit is the
- * default and is nearly always the right thing to use. You can use 12-bit if
- * you need to support image formats with more than 8 bits of resolution in a
- * color value. 16-bit should only be used for the lossless JPEG mode (not
- * currently supported). Note that 12- and 16-bit values take up twice as
- * much memory as 8-bit!
- * Note: if you select 12- or 16-bit precision, it is dangerous to turn off
- * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit
- * precision, so jchuff.c normally uses entropy optimization to compute
- * usable tables for higher precision. If you don't want to do optimization,
- * you'll have to supply different default Huffman tables.
- */
#define EIGHT_BIT_SAMPLES
#undef TWELVE_BIT_SAMPLES
@@ -295,8 +154,11 @@ typedef unsigned int JSAMPLE;
* more will cost you a BIG hit of memory, less will give wrong answers.
*/
+#ifdef RISCOS
+typedef int JCOEF;
+#else
typedef short JCOEF;
-
+#endif
/* The remaining typedefs are used for various table entries and so forth.
* They must be at least as wide as specified; but making them too big
@@ -334,6 +196,11 @@ typedef short INT16;
/* INT32 must hold signed 32-bit values; if your machine happens */
/* to have 64-bit longs, you might want to change this. */
-#ifndef XMD_H /* X11/xmd.h correctly defines INT32 */
-typedef long INT32;
+#ifdef RISCOS
+typedef int INT32;
+typedef unsigned int UINT32;
+#else
+ #ifndef XMD_H /* X11/xmd.h correctly defines INT32 */
+ typedef long INT32;
+ #endif
#endif
diff -U 3 -H -b -B -d -p -r -N -- jpeg-4/jdcolor.c cvs/c/jdcolor
--- jpeg-4/jdcolor.c 1992-08-23 20:59:39.000000000 +0100
+++ cvs/c/jdcolor 1996-11-05 09:45:02.000000000 +0000
@@ -1,3 +1,20 @@
+/* This source code in this file is licensed to You by Castle Technology
+ * Limited ("Castle") and its licensors on contractual terms and conditions
+ * ("Licence") which entitle you freely to modify and/or to distribute this
+ * source code subject to Your compliance with the terms of the Licence.
+ *
+ * This source code has been made available to You without any warranties
+ * whatsoever. Consequently, Your use, modification and distribution of this
+ * source code is entirely at Your own risk and neither Castle, its licensors
+ * nor any other person who has contributed to this source code shall be
+ * liable to You for any loss or damage which You may suffer as a result of
+ * Your use, modification or distribution of this source code.
+ *
+ * Full details of Your rights and obligations are set out in the Licence.
+ * You should have received a copy of the Licence with this source code file.
+ * If You have not received a copy, the text of the Licence is available
+ * online at www.castle-technology.co.uk/riscosbaselicence.htm
+ */
/*
* jdcolor.c
*
diff -U 3 -H -b -B -d -p -r -N -- jpeg-3/jdhuff.c cvs/c/jdhuff
--- jpeg-3/jdhuff.c 1992-03-07 00:58:45.000000000 +0000
+++ cvs/c/jdhuff 1996-11-05 09:45:02.000000000 +0000
@@ -1,3 +1,20 @@
+/* This source code in this file is licensed to You by Castle Technology
+ * Limited ("Castle") and its licensors on contractual terms and conditions
+ * ("Licence") which entitle you freely to modify and/or to distribute this
+ * source code subject to Your compliance with the terms of the Licence.
+ *
+ * This source code has been made available to You without any warranties
+ * whatsoever. Consequently, Your use, modification and distribution of this
+ * source code is entirely at Your own risk and neither Castle, its licensors
+ * nor any other person who has contributed to this source code shall be
+ * liable to You for any loss or damage which You may suffer as a result of
+ * Your use, modification or distribution of this source code.
+ *
+ * Full details of Your rights and obligations are set out in the Licence.
+ * You should have received a copy of the Licence with this source code file.
+ * If You have not received a copy, the text of the Licence is available
+ * online at www.castle-technology.co.uk/riscosbaselicence.htm
+ */
/*
* jdhuff.c
*
@@ -8,21 +25,31 @@
* This file contains Huffman entropy decoding routines.
* These routines are invoked via the methods entropy_decode
* and entropy_decoder_init/term.
+
+ * Not only hacked for use deep within RISC OS, but bits of release 4 transplanted in too.
*/
+#undef FILE_
+#define FILE_ (10000)
#include "jinclude.h"
/* Static variables to avoid passing 'round extra parameters */
+#if 0
static decompress_info_ptr dcinfo;
static INT32 get_buffer; /* current bit-extraction buffer */
static int bits_left; /* # of unused bits in it */
+#endif
+/* These have been moved to the cinfo structure, so that there are no
+static variables. */
+LOCAL int
+huff_DECODE_buildshortcut (decompress_info_ptr cinfo, HUFF_TBL * htbl); /* forward reference */
LOCAL void
-fix_huff_tbl (HUFF_TBL * htbl)
+fix_huff_tbl (decompress_info_ptr cinfo, HUFF_TBL * htbl)
/* Compute derived values for a Huffman table */
{
int p, i, l, si;
@@ -64,74 +91,122 @@ fix_huff_tbl (HUFF_TBL * htbl)
for (l = 1; l <= 16; l++) {
if (htbl->bits[l]) {
htbl->valptr[l] = p; /* huffval[] index of 1st sym of code len l */
- htbl->mincode[l] = huffcode[p]; /* minimum code of length l */
+ htbl->valptr[l] -= huffcode[p]; /* subtract value in old 'mincode' table, for speed later */
+ /* htbl->mincode[l] = huffcode[p]; */ /* minimum code of length l */
p += htbl->bits[l];
htbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */
} else {
htbl->maxcode[l] = -1;
}
}
- htbl->maxcode[17] = 0xFFFFFL; /* ensures huff_DECODE terminates */
-}
+ htbl->maxcode[17] = 0xFFFFF /*0xFFFFFL*/; /* ensures huff_DECODE terminates */
+ /* Now we build the shortcut table. Using the above, reading a huffman code
+ proceeds by reading bits one at a time, and looking up the result in a table
+ to see if it is big enough yet. The shortcut table reads the next 8 bits
+ of input, and uses this to index a table that says what to do. This table
+ is constructed by trying all 256 possibles. */
+ {
+ int i; /* index into shortcut table */
+ int h; /* the code you read */
+
+ for (i = 0; i < 256; i++) /* for each element of shortcut table */
+ {
+ cinfo->bits_left = 32;
+ cinfo->get_buffer = i << 24; /* fake the input bits */
+ h = huff_DECODE_buildshortcut(cinfo, htbl); /* the C-coded decoding doesn't use the shortcut table - we haven't built it yet! */
+ if (cinfo->bits_left < 24) /* code longer than 8 bits */
+ htbl->shortcut[i] = -1;
+ else
+ {
+ assert(h >= 0, ERROR_FATAL);
+ htbl->shortcut[i] = ((32 - cinfo->bits_left) << 24) | h; /* remember size and value */
+ }
+ }
+ cinfo->bits_left = 0;
+ cinfo->get_buffer = 0;
+ }
+}
/* Extract the next N bits from the input stream (N <= 15) */
LOCAL int
-get_bits (int nbits)
+get_bits (decompress_info_ptr cinfo, int nbits)
{
int result;
- while (nbits > bits_left) {
- int c = JGETC(dcinfo);
+ while (nbits > cinfo->bits_left) {
+ int c = JGETC(cinfo);
- get_buffer <<= 8;
- get_buffer |= c;
- bits_left += 8;
+ cinfo->get_buffer <<= 8;
+ cinfo->get_buffer |= c;
+ cinfo->bits_left += 8;
/* If it's 0xFF, check and discard stuffed zero byte */
if (c == 0xff) {
- c = JGETC(dcinfo); /* Byte stuffing */
+ c = JGETC(cinfo); /* Byte stuffing */
if (c != 0)
- ERREXIT1(dcinfo->emethods,
+ ERREXIT1(cinfo->emethods,
"Unexpected marker 0x%02x in compressed data", c);
}
}
- bits_left -= nbits;
- result = ((int) (get_buffer >> bits_left)) & ((1 << nbits) - 1);
+ cinfo->bits_left -= nbits;
+ result = ((int) (cinfo->get_buffer >> cinfo->bits_left)) & ((1 << nbits) - 1);
return result;
}
/* Macro to make things go at some speed! */
-#define get_bit() (bits_left ? \
- ((int) (get_buffer >> (--bits_left))) & 1 : \
- get_bits(1))
-
+#define get_bit(cinfo) (cinfo->bits_left ? \
+ ((int) (cinfo->get_buffer >> (--cinfo->bits_left))) & 1 : \
+ get_bits(cinfo, 1))
/* Figure F.16: extract next coded symbol from input stream */
+/* Altered version of huff_DECODE for use in constructing the shortcut table */
LOCAL int
-huff_DECODE (HUFF_TBL * htbl)
+huff_DECODE_buildshortcut (decompress_info_ptr cinfo, HUFF_TBL * htbl)
{
int l, p;
INT32 code;
- code = get_bit();
+ code = get_bit(cinfo);
+ l = 1;
+ while (code > htbl->maxcode[l] && l <= 8) {
+ code = (code << 1) + get_bit(cinfo);
+ l++;
+ }
+ if (l > 8) return -1;
+ p = (int) (htbl->valptr[l] + (code /* - htbl->mincode[l] */));
+ return (int) htbl->huffval[p];
+}
+
+#ifndef ASMHUFF
+
+LOCAL int
+huff_DECODE (decompress_info_ptr cinfo, HUFF_TBL * htbl)
+{
+ int l, p;
+ INT32 code;
+
+ code = get_bit(cinfo);
l = 1;
while (code > htbl->maxcode[l]) {
- code = (code << 1) + get_bit();
+ code = (code << 1) + get_bit(cinfo);
l++;
}
/* With garbage input we may reach the sentinel value l = 17. */
if (l > 16) {
- ERREXIT(dcinfo->emethods, "Corrupted data in JPEG file");
+ ERREXIT(cinfo->emethods, "Corrupted data in JPEG file");
}
- p = (int) (htbl->valptr[l] + (code - htbl->mincode[l]));
-
+ p = (int) (htbl->valptr[l] + (code /* - htbl->mincode[l] */));
+/*
+ tracef("Decoded huffman value=%i next_byte=0x%x bits_left=%i get_buf=0x%x.\n"
+ _ htbl->huffval[p] _ (int)cinfo->next_input_byte _ cinfo->bits_left _ cinfo->get_buffer);
+*/
return (int) htbl->huffval[p];
}
@@ -146,10 +220,59 @@ huff_DECODE (HUFF_TBL * htbl)
/* Decode a single block's worth of coefficients */
-/* Note that only the difference is returned for the DC coefficient */
+
+/* ZAG[i] is the natural-order position of the i'th element of zigzag order.
+ * If the incoming data is corrupted, huff_decode_mcu could attempt to
+ * reference values beyond the end of the array. To avoid a wild store,
+ * we put some extra zeroes after the real entries.
+ */
+
+#if 0
+
+static const short ZAG[DCTSIZE2+16] = {
+ 0, 1, 8, 16, 9, 2, 3, 10,
+ 17, 24, 32, 25, 18, 11, 4, 5,
+ 12, 19, 26, 33, 40, 48, 41, 34,
+ 27, 20, 13, 6, 7, 14, 21, 28,
+ 35, 42, 49, 56, 57, 50, 43, 36,
+ 29, 22, 15, 23, 30, 37, 44, 51,
+ 58, 59, 52, 45, 38, 31, 39, 46,
+ 53, 60, 61, 54, 47, 55, 62, 63,
+ 0, 0, 0, 0, 0, 0, 0, 0, /* extra entries in case k>63 below */
+ 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+/* 2-digit ones in decimal: */
+#define ZAG (\
+"\x00\x01\x08\x16\x09\x02\x03\x10" \
+"\x17\x24\x32\x25\x18\x11\x04\x05" \
+"\x12\x19\x26\x33\x40\x48\x41\x34" \
+"\x27\x20\x13\x06\x07\x14\x21\x28" \
+"\x35\x42\x49\x56\x57\x50\x43\x36" \
+"\x29\x22\x15\x23\x30\x37\x44\x51" \
+"\x58\x59\x52\x45\x38\x31\x39\x46" \
+"\x53\x60\x61\x54\x47\x55\x62\x63" \
+"\x00\x00\x00\x00\x00\x00\x00\x00" \
+"\x00\x00\x00\x00\x00\x00\x00\x00")
+
+#else
+
+#define ZAG (\
+"\x00\x01\x08\x10\x09\x02\x03\x0a" \
+"\x11\x18\x20\x19\x12\x0b\x04\x05" \
+"\x0c\x13\x1a\x21\x28\x30\x29\x22" \
+"\x1b\x14\x0d\x06\x07\x0e\x15\x1c" \
+"\x23\x2a\x31\x38\x39\x32\x2b\x24" \
+"\x1d\x16\x0f\x17\x1e\x25\x2c\x33" \
+"\x3a\x3b\x34\x2d\x26\x1f\x27\x2e" \
+"\x35\x3c\x3d\x36\x2f\x37\x3e\x3f" \
+"\x00\x00\x00\x00\x00\x00\x00\x00" \
+"\x00\x00\x00\x00\x00\x00\x00\x00")
+
+#endif
LOCAL void
-decode_one_block (JBLOCK block, HUFF_TBL *dctbl, HUFF_TBL *actbl)
+decode_one_block (decompress_info_ptr cinfo, JBLOCK block, HUFF_TBL *dctbl, HUFF_TBL *actbl, QUANT_TBL_PTR quanttbl, int *last_dc_val)
{
int s, k, r, n;
@@ -159,25 +282,31 @@ decode_one_block (JBLOCK block, HUFF_TBL
/* Section F.2.2.1: decode the DC coefficient difference */
- s = huff_DECODE(dctbl);
+ s = huff_DECODE(cinfo, dctbl);
if (s) {
- r = get_bits(s);
+ r = get_bits(cinfo, s);
s = huff_EXTEND(r, s);
}
- block[0] = s;
+ /* Convert DC difference to actual value, update last_dc_val */
+ s += *last_dc_val;
+ *last_dc_val = (JCOEF) s;
+ /* Descale and output the DC coefficient (assumes ZAG[0] = 0) */
+ block[0] = (JCOEF) (((JCOEF) s) * quanttbl[0]);
/* Section F.2.2.2: decode the AC coefficients */
for (k = 1; k < DCTSIZE2; k++) {
- r = huff_DECODE(actbl);
+ r = huff_DECODE(cinfo, actbl);
s = r & 15;
n = r >> 4;
if (s) {
k += n;
- r = get_bits(s);
- block[k] = huff_EXTEND(r, s);
+ r = get_bits(cinfo, s);
+ s = huff_EXTEND(r, s);
+ /* Descale coefficient and output in natural (dezigzagged) order */
+ block[ZAG[k]] = (JCOEF) (((JCOEF) s) * quanttbl[k]);
} else {
if (n != 15)
break;
@@ -186,140 +315,81 @@ decode_one_block (JBLOCK block, HUFF_TBL
}
}
-
-/*
- * Initialize for a Huffman-compressed scan.
- * This is invoked after reading the SOS marker.
- */
-
-METHODDEF void
-huff_decoder_init (decompress_info_ptr cinfo)
-{
- short ci;
- jpeg_component_info * compptr;
-
- /* Initialize static variables */
- dcinfo = cinfo;
- bits_left = 0;
-
- for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
- compptr = cinfo->cur_comp_info[ci];
- /* Make sure requested tables are present */
- if (cinfo->dc_huff_tbl_ptrs[compptr->dc_tbl_no] == NULL ||
- cinfo->ac_huff_tbl_ptrs[compptr->ac_tbl_no] == NULL)
- ERREXIT(cinfo->emethods, "Use of undefined Huffman table");
- /* Compute derived values for Huffman tables */
- /* We may do this more than once for same table, but it's not a big deal */
- fix_huff_tbl(cinfo->dc_huff_tbl_ptrs[compptr->dc_tbl_no]);
- fix_huff_tbl(cinfo->ac_huff_tbl_ptrs[compptr->ac_tbl_no]);
- /* Initialize DC predictions to 0 */
- cinfo->last_dc_val[ci] = 0;
- }
-
- /* Initialize restart stuff */
- cinfo->restarts_to_go = cinfo->restart_interval;
- cinfo->next_restart_num = 0;
-}
-
-
-/*
- * Check for a restart marker & resynchronize decoder.
- */
-
LOCAL void
-process_restart (decompress_info_ptr cinfo)
+skip_one_block (decompress_info_ptr cinfo, HUFF_TBL *dctbl, HUFF_TBL *actbl, int *last_dc_val)
+/* Like decode_one_block in its effect on *last_dc_val and the source of the input stream,
+but no block of coefficients need be produced. */
{
- int c, nbytes;
- short ci;
+ int s, k, r, n;
- /* Throw away any partial unread byte */
- bits_left = 0;
+ /* Section F.2.2.1: decode the DC coefficient difference */
- /* Scan for next JPEG marker */
- nbytes = 0;
- do {
- do { /* skip any non-FF bytes */
- nbytes++;
- c = JGETC(cinfo);
- } while (c != 0xFF);
- do { /* skip any duplicate FFs */
- nbytes++;
- c = JGETC(cinfo);
- } while (c == 0xFF);
- } while (c == 0); /* repeat if it was a stuffed FF/00 */
+ s = huff_DECODE(cinfo, dctbl);
+ if (s) {
+ r = get_bits(cinfo, s);
+ s = huff_EXTEND(r, s);
+ }
+ /* Convert DC difference to actual value, update last_dc_val */
+ s += *last_dc_val;
+ *last_dc_val = (JCOEF) s;
- if (c != (RST0 + cinfo->next_restart_num))
- ERREXIT2(cinfo->emethods, "Found 0x%02x marker instead of RST%d",
- c, cinfo->next_restart_num);
+ /* Section F.2.2.2: decode the AC coefficients */
- if (nbytes != 2)
- TRACEMS2(cinfo->emethods, 1, "Skipped %d bytes before RST%d",
- nbytes-2, cinfo->next_restart_num);
- else
- TRACEMS1(cinfo->emethods, 2, "RST%d", cinfo->next_restart_num);
+ for (k = 1; k < DCTSIZE2; k++) {
+ r = huff_DECODE(cinfo, actbl);
- /* Re-initialize DC predictions to 0 */
- for (ci = 0; ci < cinfo->comps_in_scan; ci++)
- cinfo->last_dc_val[ci] = 0;
+ s = r & 15;
+ n = r >> 4;
- /* Update restart state */
- cinfo->restarts_to_go = cinfo->restart_interval;
- cinfo->next_restart_num++;
- cinfo->next_restart_num &= 7;
+ if (s) {
+ k += n;
+ r = get_bits(cinfo, s);
+ } else {
+ if (n != 15)
+ break;
+ k += 15;
+ }
+ }
}
-
-/*
- * Decode and return one MCU's worth of Huffman-compressed coefficients.
- */
-
-METHODDEF void
-huff_decode (decompress_info_ptr cinfo, JBLOCK *MCU_data)
+LOCAL void
+huff_decode_blocks(decompress_info_ptr cinfo, JBLOCK block,
+ HUFF_TBL *dctbl, HUFF_TBL *actbl, QUANT_TBL_PTR quanttbl,
+ int *last_dc_val, int nblocks)
{
- short blkn, ci;
- jpeg_component_info * compptr;
-
- /* Account for restart interval, process restart marker if needed */
- if (cinfo->restart_interval) {
- if (cinfo->restarts_to_go == 0)
- process_restart(cinfo);
- cinfo->restarts_to_go--;
+ while (nblocks > 0)
+ {
+ decode_one_block(cinfo,block,dctbl,actbl,quanttbl,last_dc_val);
+ nblocks--;
}
+}
- for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
- ci = cinfo->MCU_membership[blkn];
- compptr = cinfo->cur_comp_info[ci];
- decode_one_block(MCU_data[blkn],
- cinfo->dc_huff_tbl_ptrs[compptr->dc_tbl_no],
- cinfo->ac_huff_tbl_ptrs[compptr->ac_tbl_no]);
- /* Convert DC difference to actual value, update last_dc_val */
- MCU_data[blkn][0] += cinfo->last_dc_val[ci];
- cinfo->last_dc_val[ci] = MCU_data[blkn][0];
+extern void
+huff_skip_blocks (decompress_info_ptr cinfo, JBLOCK block,
+ HUFF_TBL *dctbl, HUFF_TBL *actbl,
+ QUANT_TBL_PTR quanttbl, int *last_dc_val, int nblocks)
+{
+ block=block; /* unused */
+ quanttbl=quanttbl; /* unused */
+ while (nblocks > 0)
+ {
+ skip_one_block(cinfo,dctbl,actbl,last_dc_val);
+ nblocks--;
}
}
+#endif
/*
- * Finish up at the end of a Huffman-compressed scan.
+ * Initialize for a Huffman-compressed scan.
+ * This is invoked after reading the SOS marker.
*/
METHODDEF void
-huff_decoder_term (decompress_info_ptr cinfo)
+huff_decoder_init (decompress_info_ptr cinfo)
{
- /* No work needed */
-}
-
-
-/*
- * The method selection routine for Huffman entropy decoding.
- */
+ /* Initialize static variables */
+/* dcinfo = cinfo; */
+ cinfo->bits_left = 0;
-GLOBAL void
-jseldhuffman (decompress_info_ptr cinfo)
-{
- if (! cinfo->arith_code) {
- cinfo->methods->entropy_decoder_init = huff_decoder_init;
- cinfo->methods->entropy_decode = huff_decode;
- cinfo->methods->entropy_decoder_term = huff_decoder_term;
- }
}
diff -U 3 -H -b -B -d -p -r -N -- jpeg-3/jinclude.h cvs/h/jinclude
--- jpeg-3/jinclude.h 1992-03-08 03:01:21.000000000 +0000
+++ cvs/h/jinclude 1996-11-05 09:45:08.000000000 +0000
@@ -1,3 +1,20 @@
+/* This source code in this file is licensed to You by Castle Technology
+ * Limited ("Castle") and its licensors on contractual terms and conditions
+ * ("Licence") which entitle you freely to modify and/or to distribute this
+ * source code subject to Your compliance with the terms of the Licence.
+ *
+ * This source code has been made available to You without any warranties
+ * whatsoever. Consequently, Your use, modification and distribution of this
+ * source code is entirely at Your own risk and neither Castle, its licensors
+ * nor any other person who has contributed to this source code shall be
+ * liable to You for any loss or damage which You may suffer as a result of
+ * Your use, modification or distribution of this source code.
+ *
+ * Full details of Your rights and obligations are set out in the Licence.
+ * You should have received a copy of the Licence with this source code file.
+ * If You have not received a copy, the text of the Licence is available
+ * online at www.castle-technology.co.uk/riscosbaselicence.htm
+ */
/*
* jinclude.h
*
@@ -12,6 +29,10 @@
* system include files.
*/
+/* RISCOS thing - only allow this file to be included once */
+#ifndef jinclude__
+#define jinclude__
+
/*
* Normally the __STDC__ macro can be taken as indicating that the system
@@ -27,16 +48,6 @@
#endif
/*
- * <stdio.h> is included to get the FILE typedef and NULL macro.
- * Note that the core portable-JPEG files do not actually do any I/O
- * using the stdio library; only the user interface, error handler,
- * and file reading/writing modules invoke any stdio functions.
- * (Well, we did cheat a bit in jmemmgr.c, but only if MEM_STATS is defined.)
- */
-
-#include <stdio.h>
-
-/*
* We need the size_t typedef, which defines the parameter type of malloc().
* In an ANSI-conforming implementation this is provided by <stdio.h>,
* but on non-ANSI systems it's more likely to be in <sys/types.h>.
@@ -62,17 +73,6 @@
#define SIZEOF(object) ((size_t) sizeof(object))
/*
- * fread() and fwrite() are always invoked through these macros.
- * On some systems you may need to twiddle the argument casts.
- * CAUTION: argument order is different from underlying functions!
- */
-
-#define JFREAD(file,buf,sizeofbuf) \
- ((size_t) fread((void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))
-#define JFWRITE(file,buf,sizeofbuf) \
- ((size_t) fwrite((const void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))
-
-/*
* We need the memcpy() and strcmp() functions, plus memory zeroing.
* ANSI and System V implementations declare these in <string.h>.
* BSD doesn't have the mem() functions, but it does have bcopy()/bzero().
@@ -81,17 +81,17 @@
*/
#ifdef INCLUDES_ARE_ANSI
-#include <string.h>
-#define MEMZERO(voidptr,size) memset((voidptr), 0, (size))
+ #include <string.h>
+ #define MEMZERO(voidptr,size) memset((voidptr), 0, (size))
#else /* not ANSI */
-#ifdef BSD
-#include <strings.h>
-#define MEMZERO(voidptr,size) bzero((voidptr), (size))
-#define memcpy(dest,src,size) bcopy((src), (dest), (size))
-#else /* not BSD, assume Sys V or compatible */
-#include <string.h>
-#define MEMZERO(voidptr,size) memset((voidptr), 0, (size))
-#endif /* BSD */
+ #ifdef BSD
+ #include <strings.h>
+ #define MEMZERO(voidptr,size) bzero((voidptr), (size))
+ #define memcpy(dest,src,size) bcopy((src), (dest), (size))
+ #else /* not BSD, assume Sys V or compatible */
+ #include <string.h>
+ #define MEMZERO(voidptr,size) memset((voidptr), 0, (size))
+ #endif /* BSD */
#endif /* ANSI */
@@ -100,3 +100,29 @@
#include "jconfig.h"
#include "jpegdata.h"
+
+/* Assembler coded stuff */
+#ifdef ASMHUFF
+extern void
+asm_huff_decode_blocks(decompress_info_ptr cinfo, JBLOCK block,
+ HUFF_TBL *dctbl, HUFF_TBL *actbl, QUANT_TBL_PTR quanttbl,
+ int *last_dc_val, int nblocks);
+
+extern void
+asm_huff_skip_blocks(decompress_info_ptr cinfo, JBLOCK block,
+ HUFF_TBL *dctbl, HUFF_TBL *actbl, QUANT_TBL_PTR quanttbl,
+ int *last_dc_val, int nblocks);
+
+extern void panic_exit(int i);
+#endif
+
+extern void asm_j_rev_dct(decompress_info_ptr cinfo, JBLOCK block, int count);
+extern void asm_mono_convert_block(JBLOCK jblock, int *outptr, int outoffset);
+extern void asm_colour_convert_block(JBLOCK jblock, int *outptr, int outoffset);
+extern void asm_colour_convert_block_16(JBLOCK jblock, short int *outptr, int outoffset);
+extern void asm_colour_convert_block_8(JBLOCK jblock, char *outptr, int outoffset);
+extern void asm_diffuse_line_to_8bpp(int *line, int linelength, char *output, char *table32k);
+extern void asm_diffuse_to_8bpp(int *line, int linelength, char *output, char *table32k, int nlines, int linestep, int *palette_data);
+extern char *asm_get_table32k(void);
+
+#endif
diff -U 3 -H -b -B -d -p -r -N -- jpeg-3/jpegdata.h cvs/h/jpegdata
--- jpeg-3/jpegdata.h 1992-03-02 18:16:52.000000000 +0000
+++ cvs/h/jpegdata 1996-11-05 09:45:08.000000000 +0000
@@ -1,3 +1,20 @@
+/* This source code in this file is licensed to You by Castle Technology
+ * Limited ("Castle") and its licensors on contractual terms and conditions
+ * ("Licence") which entitle you freely to modify and/or to distribute this
+ * source code subject to Your compliance with the terms of the Licence.
+ *
+ * This source code has been made available to You without any warranties
+ * whatsoever. Consequently, Your use, modification and distribution of this
+ * source code is entirely at Your own risk and neither Castle, its licensors
+ * nor any other person who has contributed to this source code shall be
+ * liable to You for any loss or damage which You may suffer as a result of
+ * Your use, modification or distribution of this source code.
+ *
+ * Full details of Your rights and obligations are set out in the Licence.
+ * You should have received a copy of the Licence with this source code file.
+ * If You have not received a copy, the text of the Licence is available
+ * online at www.castle-technology.co.uk/riscosbaselicence.htm
+ */
/*
* jpegdata.h
*
@@ -6,96 +23,20 @@
* For conditions of distribution and use, see the accompanying README file.
*
* This file defines shared data structures for the various JPEG modules.
- */
-
-
-/*
- * You might need to change some of the following declarations if you are
- * using the JPEG software within a surrounding application program
- * or porting it to an unusual system.
- */
-
-
-/* If the source or destination of image data is not to be stdio streams,
- * these types may need work. You can replace them with some kind of
- * pointer or indicator that is useful to you, or just ignore 'em.
- * Note that the user interface and the various jrdxxx/jwrxxx modules
- * will also need work for non-stdio input/output.
- */
-
-typedef FILE * JFILEREF; /* source or dest of JPEG-compressed data */
-
-typedef FILE * IFILEREF; /* source or dest of non-JPEG image data */
-
-
-/* These defines are used in all function definitions and extern declarations.
- * You could modify them if you need to change function linkage conventions,
- * as is shown below for use with C++. Another application would be to make
- * all functions global for use with code profilers that require it.
- * NOTE: the C++ test does the right thing if you are reading this include
- * file in a C++ application to link to JPEG code that's been compiled with a
- * regular C compiler. I'm not sure it works if you try to compile the JPEG
- * code with C++.
+ *
+ * Seriously updated for use deep in RISCOS.
*/
#define METHODDEF static /* a function called through method pointers */
#define LOCAL static /* a function used only in its module */
-#define GLOBAL /* a function referenced thru EXTERNs */
-#ifdef __cplusplus
-#define EXTERN extern "C" /* a reference to a GLOBAL function */
-#else
-#define EXTERN extern /* a reference to a GLOBAL function */
-#endif
-
-
-/* Here is the pseudo-keyword for declaring pointers that must be "far"
- * on 80x86 machines. Most of the specialized coding for 80x86 is handled
- * by just saying "FAR *" where such a pointer is needed. In a few places
- * explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol.
- */
-
-#ifdef NEED_FAR_POINTERS
-#define FAR far
-#else
+#define GLOBAL static
+#define EXTERN static
#define FAR
-#endif
-
-
-
-/* The remaining declarations are not system-dependent, we hope. */
-
-
-/*
- * NOTE: if you have an ancient, strict-K&R C compiler, it may choke on the
- * similarly-named fields in compress_info_struct and decompress_info_struct.
- * If this happens, you can get around it by rearranging the two structs so
- * that the similarly-named fields appear first and in the same order in
- * each struct. Since such compilers are now pretty rare, we haven't done
- * this in the portable code, preferring to maintain a logical ordering.
- */
-
-
-
-/* This macro is used to declare a "method", that is, a function pointer. */
-/* We want to supply prototype parameters if the compiler can cope. */
-/* Note that the arglist parameter must be parenthesized! */
-#ifdef PROTO
#define METHOD(type,methodname,arglist) type (*methodname) arglist
-#else
-#define METHOD(type,methodname,arglist) type (*methodname) ()
-#endif
-
-/* Forward references to lists of method pointers */
-typedef struct external_methods_struct * external_methods_ptr;
-typedef struct compress_methods_struct * compress_methods_ptr;
-typedef struct decompress_methods_struct * decompress_methods_ptr;
-
/* Data structures for images containing either samples or coefficients. */
/* Note that the topmost (leftmost) index is always color component. */
-/* On 80x86 machines, the image arrays are too big for near pointers, */
-/* but the pointer arrays can fit in near memory. */
typedef JSAMPLE FAR *JSAMPROW; /* ptr to one image row of pixel samples. */
typedef JSAMPROW *JSAMPARRAY; /* ptr to some rows (a 2-D sample array) */
@@ -123,9 +62,35 @@ typedef JCOEF FAR *JCOEFPTR; /* useful i
typedef JCOEF DCTELEM;
typedef DCTELEM DCTBLOCK[DCTSIZE2];
+/* -------------------- Statistics on JPEG files ------------------------- */
-/* Types for JPEG compression parameters and working tables. */
+#ifdef STATS
+typedef struct
+{
+ int n_jblocks; /* JBLOCKs analysed */
+ int n_nonzero_coeff[DCTSIZE2]; /* no of JBLOCKs with this many nonzero coeffs,
+ given absolute DC value (not just delta). */
+
+ int n_lines_thismany_nonzero_coeffs_pass1[DCTSIZE]; /* just ac coeffs */
+ int n_lines_thismany_nonzero_coeffs_pass2[DCTSIZE];
+
+ int n_pass1_ac_zero;
+ int n_pass1_ac_dc_zero;
+ int n_pass1_ac_nonzero;
+
+ int n_pass1_even_zero; /* no of rows in pass 1 with even coeffs zero */
+ int n_pass1_odd_zero;
+ int n_pass1_odd_nonzero;
+
+ int higher_coeff_all_zero[DCTSIZE]; /* higher coeffs than this are all zero, in pass 1 */
+
+} stats_struct;
+#define IFSTATS(a) a
+#else
+#define IFSTATS(a)
+#endif
+/* ----------- Types for JPEG compression parameters and working tables. ---------- */
typedef enum { /* defines known color spaces */
CS_UNKNOWN, /* error/unspecified */
@@ -141,24 +106,24 @@ typedef struct { /* Basic info about on
/* These values are fixed over the whole image */
/* For compression, they must be supplied by the user interface; */
/* for decompression, they are read from the SOF marker. */
- short component_id; /* identifier for this component (0..255) */
- short component_index; /* its index in SOF or cinfo->comp_info[] */
- short h_samp_factor; /* horizontal sampling factor (1..4) */
- short v_samp_factor; /* vertical sampling factor (1..4) */
- short quant_tbl_no; /* quantization table selector (0..3) */
+ int /*short*/ component_id; /* identifier for this component (0..255) */
+ int /*short*/ component_index; /* its index in SOF or cinfo->comp_info[] */
+ int /*short*/ h_samp_factor; /* horizontal sampling factor (1..4) */
+ int /*short*/ v_samp_factor; /* vertical sampling factor (1..4) */
+ int /*short*/ quant_tbl_no; /* quantization table selector (0..3) */
/* These values may vary between scans */
/* For compression, they must be supplied by the user interface; */
/* for decompression, they are read from the SOS marker. */
- short dc_tbl_no; /* DC entropy table selector (0..3) */
- short ac_tbl_no; /* AC entropy table selector (0..3) */
+ int /*short*/ dc_tbl_no; /* DC entropy table selector (0..3) */
+ int /*short*/ ac_tbl_no; /* AC entropy table selector (0..3) */
/* These values are computed during compression or decompression startup */
long true_comp_width; /* component's image width in samples */
long true_comp_height; /* component's image height in samples */
/* the above are the logical dimensions of the subsampled image */
/* These values are computed before starting a scan of the component */
- short MCU_width; /* number of blocks per MCU, horizontally */
- short MCU_height; /* number of blocks per MCU, vertically */
- short MCU_blocks; /* MCU_width * MCU_height */
+ int /*short*/ MCU_width; /* number of blocks per MCU, horizontally */
+ int /*short*/ MCU_height; /* number of blocks per MCU, vertically */
+ int /*short*/ MCU_blocks; /* MCU_width * MCU_height */
long subsampled_width; /* image width in samples, after expansion */
long subsampled_height; /* image height in samples, after expansion */
/* the above are the true_comp_xxx values rounded up to multiples of */
@@ -175,11 +140,7 @@ typedef struct { /* Basic info about on
* quantization values is a significant chunk of the runtime).
* Note: the values in a QUANT_TBL are always given in zigzag order.
*/
-#ifdef EIGHT_BIT_SAMPLES
-typedef INT16 QUANT_VAL; /* element of a quantization table */
-#else
-typedef UINT16 QUANT_VAL; /* element of a quantization table */
-#endif
+typedef int QUANT_VAL;
typedef QUANT_VAL QUANT_TBL[DCTSIZE2]; /* A quantization table */
typedef QUANT_VAL * QUANT_TBL_PTR; /* pointer to same */
@@ -189,22 +151,24 @@ typedef struct { /* A Huffman coding ta
UINT8 bits[17]; /* bits[k] = # of symbols with codes of */
/* length k bits; bits[0] is unused */
UINT8 huffval[256]; /* The symbols, in order of incr code length */
- /* This field is used only during compression. It's initialized FALSE when
- * the table is created, and set TRUE when it's been output to the file.
- */
- boolean sent_table; /* TRUE when table has been output */
+
/* The remaining fields are computed from the above to allow more efficient
* coding and decoding. These fields should be considered private to the
* Huffman compression & decompression modules.
*/
- /* encoding tables: */
- UINT16 ehufco[256]; /* code for each symbol */
- char ehufsi[256]; /* length of code for each symbol */
/* decoding tables: (element [0] of each array is unused) */
- UINT16 mincode[17]; /* smallest code of length k */
+#if 0
+ UINT32 /*UINT16*/ mincode[17]; /* smallest code of length k */
+#endif
INT32 maxcode[18]; /* largest code of length k (-1 if none) */
/* (maxcode[17] is a sentinel to ensure huff_DECODE terminates) */
- short valptr[17]; /* huffval[] index of 1st symbol of length k */
+ int /*short*/ valptr[17]; /* huffval[] index of 1st symbol of length k */
+ /* with value of mincode[k] from above subtracted */
+
+ int shortcut[256]; /* shortcuts the actual reading of huffman values - indexed
+ by the next 8 bits in the bit stream an entry tells you
+ how long the next entry is. This allows you to read
+ the vast majority of huffman codes at a single step. */
} HUFF_TBL;
@@ -215,169 +179,70 @@ typedef struct { /* A Huffman coding ta
#define MAX_SAMP_FACTOR 4 /* JPEG limit on sampling factors */
#define MAX_BLOCKS_IN_MCU 10 /* JPEG limit on # of blocks in an MCU */
+/* ----------- Remember a precise position in the huffman stream. ------------------ */
+typedef struct
+{
+ int bit_pointer; /* (next_input_byte-input_buffer)*32 + bits_left */
+ int get_buffer;
+ short int last_dc_val0; /* NB NOT dequantised */
+ short int last_dc_val1;
+ short int last_dc_val2;
+ short int last_dc_val3; /* in case we ever do CMYK */
+ short int restarts_to_go;
+ short int next_restart_num;
+} huff_pointer;
-/* Working data for compression */
-
-struct compress_info_struct {
-/*
- * All of these fields shall be established by the user interface before
- * calling jpeg_compress, or by the input_init or c_ui_method_selection
- * methods.
- * Most parameters can be set to reasonable defaults by j_c_defaults.
- * Note that the UI must supply the storage for the main methods struct,
- * though it sets only a few of the methods there.
- */
- compress_methods_ptr methods; /* Points to list of methods to use */
-
- external_methods_ptr emethods; /* Points to list of methods to use */
-
- IFILEREF input_file; /* tells input routines where to read image */
- JFILEREF output_file; /* tells output routines where to write JPEG */
-
- long image_width; /* input image width */
- long image_height; /* input image height */
- short input_components; /* # of color components in input image */
-
- short data_precision; /* bits of precision in image data */
-
- COLOR_SPACE in_color_space; /* colorspace of input file */
- COLOR_SPACE jpeg_color_space; /* colorspace of JPEG file */
-
- double input_gamma; /* image gamma of input file */
-
- boolean write_JFIF_header; /* should a JFIF marker be written? */
- /* These three values are not used by the JPEG code, only copied */
- /* into the JFIF APP0 marker. density_unit can be 0 for unknown, */
- /* 1 for dots/inch, or 2 for dots/cm. Note that the pixel aspect */
- /* ratio is defined by X_density/Y_density even when density_unit=0. */
- UINT8 density_unit; /* JFIF code for pixel size units */
- UINT16 X_density; /* Horizontal pixel density */
- UINT16 Y_density; /* Vertical pixel density */
-
- short num_components; /* # of color components in JPEG image */
- jpeg_component_info * comp_info;
- /* comp_info[i] describes component that appears i'th in SOF */
-
- QUANT_TBL_PTR quant_tbl_ptrs[NUM_QUANT_TBLS];
- /* ptrs to coefficient quantization tables, or NULL if not defined */
-
- HUFF_TBL * dc_huff_tbl_ptrs[NUM_HUFF_TBLS];
- HUFF_TBL * ac_huff_tbl_ptrs[NUM_HUFF_TBLS];
- /* ptrs to Huffman coding tables, or NULL if not defined */
-
- UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arithmetic-coding tables */
- UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arithmetic-coding tables */
- UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arithmetic-coding tables */
-
- boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */
- boolean interleave; /* TRUE=interleaved output, FALSE=not */
- boolean optimize_coding; /* TRUE=optimize entropy encoding parms */
- boolean CCIR601_sampling; /* TRUE=first samples are cosited */
-
- UINT16 restart_interval;/* MDUs per restart interval, or 0 for no restart */
-
-/*
- * These fields are computed during jpeg_compress startup
- */
- short max_h_samp_factor; /* largest h_samp_factor */
- short max_v_samp_factor; /* largest v_samp_factor */
-
-/*
- * These fields may be useful for progress monitoring
- */
-
- int total_passes; /* number of passes expected */
- int completed_passes; /* number of passes completed so far */
-
-/*
- * These fields are valid during any one scan
- */
- short comps_in_scan; /* # of JPEG components output this time */
- jpeg_component_info * cur_comp_info[MAX_COMPS_IN_SCAN];
- /* *cur_comp_info[i] describes component that appears i'th in SOS */
-
- long MCUs_per_row; /* # of MCUs across the image */
- long MCU_rows_in_scan; /* # of MCU rows in the image */
-
- short blocks_in_MCU; /* # of DCT blocks per MCU */
- short MCU_membership[MAX_BLOCKS_IN_MCU];
- /* MCU_membership[i] is index in cur_comp_info of component owning */
- /* i'th block in an MCU */
-
- /* these fields are private data for the entropy encoder */
- JCOEF last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each comp */
- JCOEF last_dc_diff[MAX_COMPS_IN_SCAN]; /* last DC diff for each comp */
- UINT16 restarts_to_go; /* MDUs left in this restart interval */
- short next_restart_num; /* # of next RSTn marker (0..7) */
-};
-
-typedef struct compress_info_struct * compress_info_ptr;
-
+/* ------------- Error codes for various forms of unacceptable JPEG file ------------- */
+#define E_PRE_NOT_8 1 /* Data precision not 8 */
+#define E_RESTART 2 /* Restart interval not 0 */
+#define E_MULTI_SCAN 3 /* Multi-scan file */
+#define E_TOO_HIGH 4 /* Image too high, max is %i pixels */
+#define E_BAD_SAMPLE 5 /* Bad sample factor */
+#define E_HEIGHT 6 /* Height is %i, not as specified */
+#define E_WIDTH 7 /* Width is %i, not as specified */
+#define E_COLOUR 8 /* Bad colour space (%i), not grey or YUV */
+#define E_COMPONENTS 9 /* Bad number (%i) of components, only 1 or 3 allowed */
+#define E_TOO_WIDE 10 /* Image too wide, max is %i pixels */
-/* Working data for decompression */
+/* ------------- Working data for decompression ---------------------------------- */
struct decompress_info_struct {
-/*
- * These fields shall be established by the user interface before
- * calling jpeg_decompress.
- * Most parameters can be set to reasonable defaults by j_d_defaults.
- * Note that the UI must supply the storage for the main methods struct,
- * though it sets only a few of the methods there.
- */
- decompress_methods_ptr methods; /* Points to list of methods to use */
-
- external_methods_ptr emethods; /* Points to list of methods to use */
- JFILEREF input_file; /* tells input routines where to read JPEG */
- IFILEREF output_file; /* tells output routines where to write image */
-
- /* these can be set at d_ui_method_selection time: */
+ int error_code; /* Returned err code, 0 if no error */
+ int error_argument1; /* Supplementary error data */
+ int error_argument2; /* Supplementary error data */
- COLOR_SPACE out_color_space; /* colorspace of output */
+ char *workspace_UNUSED; /* For band buffer and things. (no, implicitly at end of this space now) */
+ int workspace_size; /* number of bytes */
+/* up to here appears in sources.SprExtend */
- double output_gamma; /* image gamma wanted in output */
+ int /*long*/ image_width; /* overall image width */
+ int /*long*/ image_height; /* overall image height */
+ COLOR_SPACE jpeg_color_space; /* colorspace of JPEG file */
+/* up to here is replicated somewhat in CFSI-JPEG's interface */
- boolean quantize_colors; /* T if output is a colormapped format */
- /* the following are ignored if not quantize_colors: */
- boolean two_pass_quantize; /* use two-pass color quantization? */
- boolean use_dithering; /* want color dithering? */
- int desired_number_of_colors; /* max number of colors to use */
+ char *table32k; /* the 16bpp->8bpp 32K lookup table, if you need it. */
+ BOOL table32k_unavailable; /* Set if we ever failed to get table32k.
+ This means we're probably on an old OS, so the
+ table will never be available. */
- boolean do_block_smoothing; /* T = apply cross-block smoothing */
- boolean do_pixel_smoothing; /* T = apply post-subsampling smoothing */
+ int *band_buffer; /* Large buffer into which the colour data goes. */
+ /* We construct one strip, 8 or 16 pixels high, across the image. */
+ int band_buffer_size; /* Must be a multiple of 16 */
-/*
- * These fields are used for efficient buffering of data between read_jpeg_data
- * and the entropy decoding object. By using a shared buffer, we avoid copying
- * data and eliminate the need for an "unget" operation at the end of a scan.
- * The actual source of the data is known only to read_jpeg_data; see the
- * JGETC macro, below.
- * Note: the user interface is expected to allocate the input_buffer and
- * initialize bytes_in_buffer to 0. Also, for JFIF/raw-JPEG input, the UI
- * actually supplies the read_jpeg_data method. This is all handled by
- * j_d_defaults in a typical implementation.
- */
char * input_buffer; /* start of buffer (private to input code) */
char * next_input_byte; /* => next byte to read from buffer */
- int bytes_in_buffer; /* # of bytes remaining in buffer */
-
-/*
- * These fields are set by read_file_header or read_scan_header
- */
- long image_width; /* overall image width */
- long image_height; /* overall image height */
-
- short data_precision; /* bits of precision in image data */
+ char * buffer_end; /* pointer to end of buffer */
- COLOR_SPACE jpeg_color_space; /* colorspace of JPEG file */
+ int data_precision; /* bits of precision in image data */
/* These three values are not used by the JPEG code, merely copied */
/* from the JFIF APP0 marker (if any). */
- UINT8 density_unit; /* JFIF code for pixel size units */
- UINT16 X_density; /* Horizontal pixel density */
- UINT16 Y_density; /* Vertical pixel density */
+ UINT32 /*UINT8*/ density_unit; /* JFIF code for pixel size units */
+ UINT32 /*UINT16*/ X_density; /* Horizontal pixel density */
+ UINT32 /*UINT16*/ Y_density; /* Vertical pixel density */
- short num_components; /* # of color components in JPEG image */
+ int /*short*/ num_components; /* # of color components in JPEG image */
jpeg_component_info * comp_info;
/* comp_info[i] describes component that appears i'th in SOF */
@@ -395,462 +260,113 @@ struct decompress_info_struct {
boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */
boolean CCIR601_sampling; /* TRUE=first samples are cosited */
- UINT16 restart_interval;/* MDUs per restart interval, or 0 for no restart */
-
-/*
- * These fields are computed during jpeg_decompress startup
- */
- short max_h_samp_factor; /* largest h_samp_factor */
- short max_v_samp_factor; /* largest v_samp_factor */
-
- short color_out_comps; /* # of color components output by color_convert */
- /* (need not match num_components) */
- short final_out_comps; /* # of color components sent to put_pixel_rows */
- /* (1 when quantizing colors, else same as color_out_comps) */
-
-/*
- * When quantizing colors, the color quantizer leaves a pointer to the output
- * colormap in these fields. The colormap is valid from the time put_color_map
- * is called (must be before any put_pixel_rows calls) until shutdown (more
- * specifically, until free_all is called to release memory).
- */
- int actual_number_of_colors; /* actual number of entries */
- JSAMPARRAY colormap; /* NULL if not valid */
- /* map has color_out_comps rows * actual_number_of_colors columns */
-
-/*
- * These fields may be useful for progress monitoring
- */
-
- int total_passes; /* number of passes expected */
- int completed_passes; /* number of passes completed so far */
+ UINT32 /*UINT16*/ restart_interval;/* MDUs per restart interval, or 0 for no restart */
+ int restarts_to_go;
+ int next_restart_num;
/*
* These fields are valid during any one scan
*/
- short comps_in_scan; /* # of JPEG components input this time */
+ int /*short*/ comps_in_scan; /* # of JPEG components input this time */
jpeg_component_info * cur_comp_info[MAX_COMPS_IN_SCAN];
/* *cur_comp_info[i] describes component that appears i'th in SOS */
long MCUs_per_row; /* # of MCUs across the image */
long MCU_rows_in_scan; /* # of MCU rows in the image */
- short blocks_in_MCU; /* # of DCT blocks per MCU */
- short MCU_membership[MAX_BLOCKS_IN_MCU];
- /* MCU_membership[i] is index in cur_comp_info of component owning */
- /* i'th block in an MCU */
-
/* these fields are private data for the entropy encoder */
- JCOEF last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each comp */
- JCOEF last_dc_diff[MAX_COMPS_IN_SCAN]; /* last DC diff for each comp */
- UINT16 restarts_to_go; /* MDUs left in this restart interval */
- short next_restart_num; /* # of next RSTn marker (0..7) */
-};
-
-typedef struct decompress_info_struct * decompress_info_ptr;
-
-
-/* Macros for reading data from the decompression input buffer */
-
-#ifdef CHAR_IS_UNSIGNED
-#define JGETC(cinfo) ( --(cinfo)->bytes_in_buffer < 0 ? \
- (*(cinfo)->methods->read_jpeg_data) (cinfo) : \
- (int) (*(cinfo)->next_input_byte++) )
-#else
-#define JGETC(cinfo) ( --(cinfo)->bytes_in_buffer < 0 ? \
- (*(cinfo)->methods->read_jpeg_data) (cinfo) : \
- (int) (*(cinfo)->next_input_byte++) & 0xFF )
-#endif
-
-#define JUNGETC(ch,cinfo) ((cinfo)->bytes_in_buffer++, \
- *(--((cinfo)->next_input_byte)) = (ch))
-
-#define MIN_UNGET 4 /* may always do at least 4 JUNGETCs */
-
-
-/* A virtual image has a control block whose contents are private to the
- * memory manager module (and may differ between managers). The rest of the
- * code only refers to virtual images by these pointer types, and never
- * dereferences the pointer.
- */
-
-typedef struct big_sarray_control * big_sarray_ptr;
-typedef struct big_barray_control * big_barray_ptr;
-
-/* Although a real ANSI C compiler can deal perfectly well with pointers to
- * unspecified structures (see "incomplete types" in the spec), a few pre-ANSI
- * and pseudo-ANSI compilers get confused. To keep one of these bozos happy,
- * add -DINCOMPLETE_TYPES_BROKEN to CFLAGS in your Makefile. Then we will
- * pseudo-define the structs as containing a single "dummy" field.
- * The memory managers #define AM_MEMORY_MANAGER before including this file,
- * so that they can make their own definitions of the structs.
- */
-
-#ifdef INCOMPLETE_TYPES_BROKEN
-#ifndef AM_MEMORY_MANAGER
-struct big_sarray_control { long dummy; };
-struct big_barray_control { long dummy; };
-#endif
-#endif
-
-
-/* Method types that need typedefs */
-
-typedef METHOD(void, MCU_output_method_ptr, (compress_info_ptr cinfo,
- JBLOCK *MCU_data));
-typedef METHOD(void, MCU_output_caller_ptr, (compress_info_ptr cinfo,
- MCU_output_method_ptr output_method));
-typedef METHOD(void, subsample_ptr, (compress_info_ptr cinfo,
- int which_component,
- long input_cols, int input_rows,
- long output_cols, int output_rows,
- JSAMPARRAY above,
- JSAMPARRAY input_data,
- JSAMPARRAY below,
- JSAMPARRAY output_data));
-typedef METHOD(void, unsubsample_ptr, (decompress_info_ptr cinfo,
- int which_component,
- long input_cols, int input_rows,
- long output_cols, int output_rows,
- JSAMPARRAY above,
- JSAMPARRAY input_data,
- JSAMPARRAY below,
- JSAMPARRAY output_data));
-typedef METHOD(void, quantize_method_ptr, (decompress_info_ptr cinfo,
- int num_rows,
- JSAMPIMAGE input_data,
- JSAMPARRAY output_workspace));
-typedef METHOD(void, quantize_caller_ptr, (decompress_info_ptr cinfo,
- quantize_method_ptr quantize_method));
+ JCOEF last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each comp - NOT dequantized yet */
+ int current_huff_pointer; /* Currently loaded band, or -1 if none. */
+ int xmin;
+ int xmax; /* Min and max x pixels required: clip as early
+ as possible. */
+ int options;
-/* These structs contain function pointers for the various JPEG methods. */
+ /* Statics moved in from the huffman decoding */
+ int get_buffer;
+ int bits_left;
-/* Routines to be provided by the surrounding application, rather than the
- * portable JPEG code proper. These are the same for compression and
- * decompression.
- */
+ /* Random check words to look for the same sprite over again */
+ int check1;
+ int check2;
+ int check3;
-struct external_methods_struct {
- /* User interface: error exit and trace message routines */
- /* NOTE: the string msgtext parameters will eventually be replaced */
- /* by an enumerated-type code so that non-English error messages */
- /* can be substituted easily. This will not be done until all the */
- /* code is in place, so that we know what messages are needed. */
- METHOD(void, error_exit, (const char *msgtext));
- METHOD(void, trace_message, (const char *msgtext));
+ IFSTATS(stats_struct stats;) /* Gathering statistics */
- /* Working data for error/trace facility */
- /* See macros below for the usage of these variables */
- int trace_level; /* level of detail of tracing messages */
- /* Use level 0 for unsuppressable messages (nonfatal errors) */
- /* Use levels 1, 2, 3 for successively more detailed trace options */
+ JBLOCK jblocks[7]; /* YYYYUV blocks, and one spare at the front */
- int message_parm[8]; /* store numeric parms for messages here */
+#define HPOINTERS 200 /* max picture depth 16*this for colour, 8*this for mono, in pixels */
+ huff_pointer *huff_pointers;
+ /* An array of information every 16 pixel lines, which
+ allows us to start decoding the file at that point. This
+ allows reasonably quick random access to anywhere in the file. */
- /* Memory management */
- /* NB: alloc routines never return NULL. They exit to */
- /* error_exit if not successful. */
- METHOD(void *, alloc_small, (size_t sizeofobject));
- METHOD(void, free_small, (void *ptr));
- METHOD(void FAR *, alloc_medium, (size_t sizeofobject));
- METHOD(void, free_medium, (void FAR *ptr));
- METHOD(JSAMPARRAY, alloc_small_sarray, (long samplesperrow,
- long numrows));
- METHOD(void, free_small_sarray, (JSAMPARRAY ptr));
- METHOD(JBLOCKARRAY, alloc_small_barray, (long blocksperrow,
- long numrows));
- METHOD(void, free_small_barray, (JBLOCKARRAY ptr));
- METHOD(big_sarray_ptr, request_big_sarray, (long samplesperrow,
- long numrows,
- long unitheight));
- METHOD(big_barray_ptr, request_big_barray, (long blocksperrow,
- long numrows,
- long unitheight));
- METHOD(void, alloc_big_arrays, (long extra_small_samples,
- long extra_small_blocks,
- long extra_medium_space));
- METHOD(JSAMPARRAY, access_big_sarray, (big_sarray_ptr ptr,
- long start_row,
- boolean writable));
- METHOD(JBLOCKARRAY, access_big_barray, (big_barray_ptr ptr,
- long start_row,
- boolean writable));
- METHOD(void, free_big_sarray, (big_sarray_ptr ptr));
- METHOD(void, free_big_barray, (big_barray_ptr ptr));
- METHOD(void, free_all, (void));
+ /* Space always needed, and pointed at by some of the pointers above. */
- long max_memory_to_use; /* maximum amount of memory to use */
+ jpeg_component_info s_cur_comp_info[MAX_COMPS_IN_SCAN];
+ QUANT_TBL s_quant_tbl[NUM_QUANT_TBLS];
+ HUFF_TBL s_dc_huff_tbl[NUM_HUFF_TBLS];
+ HUFF_TBL s_ac_huff_tbl[NUM_HUFF_TBLS];
};
-/* Macros to simplify using the error and trace message stuff */
-/* The first parameter is generally cinfo->emethods */
-
-#define ERREXIT(emeth,msg) ((*(emeth)->error_exit) (msg))
-#define ERREXIT1(emeth,msg,p1) ((emeth)->message_parm[0] = (p1), \
- (*(emeth)->error_exit) (msg))
-#define ERREXIT2(emeth,msg,p1,p2) ((emeth)->message_parm[0] = (p1), \
- (emeth)->message_parm[1] = (p2), \
- (*(emeth)->error_exit) (msg))
-#define ERREXIT3(emeth,msg,p1,p2,p3) ((emeth)->message_parm[0] = (p1), \
- (emeth)->message_parm[1] = (p2), \
- (emeth)->message_parm[2] = (p3), \
- (*(emeth)->error_exit) (msg))
-#define ERREXIT4(emeth,msg,p1,p2,p3,p4) ((emeth)->message_parm[0] = (p1), \
- (emeth)->message_parm[1] = (p2), \
- (emeth)->message_parm[2] = (p3), \
- (emeth)->message_parm[3] = (p4), \
- (*(emeth)->error_exit) (msg))
-
-#define MAKESTMT(stuff) do { stuff } while (0)
-
-#define TRACEMS(emeth,lvl,msg) \
- MAKESTMT( if ((emeth)->trace_level >= (lvl)) { \
- (*(emeth)->trace_message) (msg); } )
-#define TRACEMS1(emeth,lvl,msg,p1) \
- MAKESTMT( if ((emeth)->trace_level >= (lvl)) { \
- (emeth)->message_parm[0] = (p1); \
- (*(emeth)->trace_message) (msg); } )
-#define TRACEMS2(emeth,lvl,msg,p1,p2) \
- MAKESTMT( if ((emeth)->trace_level >= (lvl)) { \
- (emeth)->message_parm[0] = (p1); \
- (emeth)->message_parm[1] = (p2); \
- (*(emeth)->trace_message) (msg); } )
-#define TRACEMS3(emeth,lvl,msg,p1,p2,p3) \
- MAKESTMT( if ((emeth)->trace_level >= (lvl)) { \
- int * _mp = (emeth)->message_parm; \
- *_mp++ = (p1); *_mp++ = (p2); *_mp = (p3); \
- (*(emeth)->trace_message) (msg); } )
-#define TRACEMS4(emeth,lvl,msg,p1,p2,p3,p4) \
- MAKESTMT( if ((emeth)->trace_level >= (lvl)) { \
- int * _mp = (emeth)->message_parm; \
- *_mp++ = (p1); *_mp++ = (p2); *_mp++ = (p3); *_mp = (p4); \
- (*(emeth)->trace_message) (msg); } )
-#define TRACEMS8(emeth,lvl,msg,p1,p2,p3,p4,p5,p6,p7,p8) \
- MAKESTMT( if ((emeth)->trace_level >= (lvl)) { \
- int * _mp = (emeth)->message_parm; \
- *_mp++ = (p1); *_mp++ = (p2); *_mp++ = (p3); *_mp++ = (p4); \
- *_mp++ = (p5); *_mp++ = (p6); *_mp++ = (p7); *_mp = (p8); \
- (*(emeth)->trace_message) (msg); } )
-
-
-/* Methods used during JPEG compression. */
+typedef struct decompress_info_struct * decompress_info_ptr;
-struct compress_methods_struct {
- /* Hook for user interface to get control after input_init */
- METHOD(void, c_ui_method_selection, (compress_info_ptr cinfo));
- /* Hook for user interface to do progress monitoring */
- METHOD(void, progress_monitor, (compress_info_ptr cinfo,
- long loopcounter, long looplimit));
- /* Input image reading & conversion to standard form */
- METHOD(void, input_init, (compress_info_ptr cinfo));
- METHOD(void, get_input_row, (compress_info_ptr cinfo,
- JSAMPARRAY pixel_row));
- METHOD(void, input_term, (compress_info_ptr cinfo));
- /* Color space and gamma conversion */
- METHOD(void, colorin_init, (compress_info_ptr cinfo));
- METHOD(void, get_sample_rows, (compress_info_ptr cinfo,
- int rows_to_read,
- JSAMPIMAGE image_data));
- METHOD(void, colorin_term, (compress_info_ptr cinfo));
- /* Expand picture data at edges */
- METHOD(void, edge_expand, (compress_info_ptr cinfo,
- long input_cols, int input_rows,
- long output_cols, int output_rows,
- JSAMPIMAGE image_data));
- /* Subsample pixel values of a single component */
- /* There can be a different subsample method for each component */
- METHOD(void, subsample_init, (compress_info_ptr cinfo));
- subsample_ptr subsample[MAX_COMPS_IN_SCAN];
- METHOD(void, subsample_term, (compress_info_ptr cinfo));
- /* Extract samples in MCU order, process & hand off to output_method */
- /* The input is always exactly N MCU rows worth of data */
- METHOD(void, extract_init, (compress_info_ptr cinfo));
- METHOD(void, extract_MCUs, (compress_info_ptr cinfo,
- JSAMPIMAGE image_data,
- int num_mcu_rows,
- MCU_output_method_ptr output_method));
- METHOD(void, extract_term, (compress_info_ptr cinfo));
- /* Entropy encoding parameter optimization */
- METHOD(void, entropy_optimize, (compress_info_ptr cinfo,
- MCU_output_caller_ptr source_method));
- /* Entropy encoding */
- METHOD(void, entropy_encoder_init, (compress_info_ptr cinfo));
- METHOD(void, entropy_encode, (compress_info_ptr cinfo,
- JBLOCK *MCU_data));
- METHOD(void, entropy_encoder_term, (compress_info_ptr cinfo));
- /* JPEG file header construction */
- METHOD(void, write_file_header, (compress_info_ptr cinfo));
- METHOD(void, write_scan_header, (compress_info_ptr cinfo));
- METHOD(void, write_jpeg_data, (compress_info_ptr cinfo,
- char *dataptr,
- int datacount));
- METHOD(void, write_scan_trailer, (compress_info_ptr cinfo));
- METHOD(void, write_file_trailer, (compress_info_ptr cinfo));
- /* Pipeline control */
- METHOD(void, c_pipeline_controller, (compress_info_ptr cinfo));
- METHOD(void, entropy_output, (compress_info_ptr cinfo,
- char *dataptr,
- int datacount));
- /* Overall control */
- METHOD(void, c_per_scan_method_selection, (compress_info_ptr cinfo));
-};
-/* Methods used during JPEG decompression. */
+/* Macros for reading data from the decompression input buffer */
-struct decompress_methods_struct {
- /* Hook for user interface to get control after reading file header */
- METHOD(void, d_ui_method_selection, (decompress_info_ptr cinfo));
- /* Hook for user interface to do progress monitoring */
- METHOD(void, progress_monitor, (decompress_info_ptr cinfo,
- long loopcounter, long looplimit));
- /* JPEG file scanning */
- METHOD(void, read_file_header, (decompress_info_ptr cinfo));
- METHOD(boolean, read_scan_header, (decompress_info_ptr cinfo));
- METHOD(int, read_jpeg_data, (decompress_info_ptr cinfo));
- METHOD(void, read_scan_trailer, (decompress_info_ptr cinfo));
- METHOD(void, read_file_trailer, (decompress_info_ptr cinfo));
- /* Entropy decoding */
- METHOD(void, entropy_decoder_init, (decompress_info_ptr cinfo));
- METHOD(void, entropy_decode, (decompress_info_ptr cinfo,
- JBLOCK *MCU_data));
- METHOD(void, entropy_decoder_term, (decompress_info_ptr cinfo));
- /* MCU disassembly: fetch MCUs from entropy_decode, build coef array */
- /* The reverse_DCT step is in the same module for symmetry reasons */
- METHOD(void, disassemble_init, (decompress_info_ptr cinfo));
- METHOD(void, disassemble_MCU, (decompress_info_ptr cinfo,
- JBLOCKIMAGE image_data));
- METHOD(void, reverse_DCT, (decompress_info_ptr cinfo,
- JBLOCKIMAGE coeff_data,
- JSAMPIMAGE output_data, int start_row));
- METHOD(void, disassemble_term, (decompress_info_ptr cinfo));
- /* Cross-block smoothing */
- METHOD(void, smooth_coefficients, (decompress_info_ptr cinfo,
- jpeg_component_info *compptr,
- JBLOCKROW above,
- JBLOCKROW currow,
- JBLOCKROW below,
- JBLOCKROW output));
- /* Un-subsample pixel values of a single component */
- /* There can be a different unsubsample method for each component */
- METHOD(void, unsubsample_init, (decompress_info_ptr cinfo));
- unsubsample_ptr unsubsample[MAX_COMPS_IN_SCAN];
- METHOD(void, unsubsample_term, (decompress_info_ptr cinfo));
- /* Color space and gamma conversion */
- METHOD(void, colorout_init, (decompress_info_ptr cinfo));
- METHOD(void, color_convert, (decompress_info_ptr cinfo,
- int num_rows, long num_cols,
- JSAMPIMAGE input_data,
- JSAMPIMAGE output_data));
- METHOD(void, colorout_term, (decompress_info_ptr cinfo));
- /* Color quantization */
- METHOD(void, color_quant_init, (decompress_info_ptr cinfo));
- METHOD(void, color_quantize, (decompress_info_ptr cinfo,
- int num_rows,
- JSAMPIMAGE input_data,
- JSAMPARRAY output_data));
- METHOD(void, color_quant_prescan, (decompress_info_ptr cinfo,
- int num_rows,
- JSAMPIMAGE image_data,
- JSAMPARRAY workspace));
- METHOD(void, color_quant_doit, (decompress_info_ptr cinfo,
- quantize_caller_ptr source_method));
- METHOD(void, color_quant_term, (decompress_info_ptr cinfo));
- /* Output image writing */
- METHOD(void, output_init, (decompress_info_ptr cinfo));
- METHOD(void, put_color_map, (decompress_info_ptr cinfo,
- int num_colors, JSAMPARRAY colormap));
- METHOD(void, put_pixel_rows, (decompress_info_ptr cinfo,
- int num_rows,
- JSAMPIMAGE pixel_data));
- METHOD(void, output_term, (decompress_info_ptr cinfo));
- /* Pipeline control */
- METHOD(void, d_pipeline_controller, (decompress_info_ptr cinfo));
- /* Overall control */
- METHOD(void, d_per_scan_method_selection, (decompress_info_ptr cinfo));
-};
+/* The buffer contains the entire file */
+#define JGETC(cinfo) (int) ((cinfo)->next_input_byte >= (cinfo)->buffer_end ? 255 : *(cinfo)->next_input_byte++)
+/* Macros to simplify using the error and trace message stuff */
+/* The first parameter is generally cinfo->emethods, left undisturbed in
+ c.jrdjfif but not used here. */
-/* External declarations for routines that aren't called via method ptrs. */
-/* Note: use "j" as first char of names to minimize namespace pollution. */
-/* The PP macro hides prototype parameters from compilers that can't cope. */
+/* The variable FILE_ is used to identify source files, smaller than __FILE__ (a bit!) for
+non-debugging code. */
+#define EXIT exit(FILE_+__LINE__);
-#ifdef PROTO
-#define PP(arglist) arglist
+#ifdef DEBUG
+ #ifdef EMBED
+ #define TRACEMS(emeth,lvl,msg) {sprintf(0, msg); newline();}
+ #define TRACEMS1(emeth,lvl,msg,p1) {sprintf(0, msg,p1); newline();}
+ #define TRACEMS2(emeth,lvl,msg,p1,p2) {sprintf(0, msg,p1,p2); newline();}
+ #define TRACEMS3(emeth,lvl,msg,p1,p2,p3) {sprintf(0, msg,p1,p2,p3); newline();}
+ #define TRACEMS4(emeth,lvl,msg,p1,p2,p3,p4) {sprintf(0, msg,p1,p2,p3,p4); newline();}
+ #define TRACEMS8(emeth,lvl,msg,p1,p2,p3,p4,p5,p6,p7,p8) {sprintf(0, msg,p1,p2,p3,p4,p5,p6,p7,p8); newline();}
+ #else
+ #define TRACEMS(emeth,lvl,msg) {if (verbose) {printf(msg); printf("\n");}}
+ #define TRACEMS1(emeth,lvl,msg,p1) {if (verbose) {printf(msg,p1); printf("\n");}}
+ #define TRACEMS2(emeth,lvl,msg,p1,p2) {if (verbose) {printf(msg,p1,p2); printf("\n");}}
+ #define TRACEMS3(emeth,lvl,msg,p1,p2,p3) {if (verbose) {printf(msg,p1,p2,p3); printf("\n");}}
+ #define TRACEMS4(emeth,lvl,msg,p1,p2,p3,p4) {if (verbose) {printf(msg,p1,p2,p3,p4); printf("\n");}}
+ #define TRACEMS8(emeth,lvl,msg,p1,p2,p3,p4,p5,p6,p7,p8) {if (verbose) {printf(msg,p1,p2,p3,p4,p5,p6,p7,p8); printf("\n");}}
+ #endif
#else
-#define PP(arglist) ()
+ #define TRACEMS(emeth,lvl,msg)
+ #define TRACEMS1(emeth,lvl,msg,p1)
+ #define TRACEMS2(emeth,lvl,msg,p1,p2)
+ #define TRACEMS3(emeth,lvl,msg,p1,p2,p3)
+ #define TRACEMS4(emeth,lvl,msg,p1,p2,p3,p4)
+ #define TRACEMS8(emeth,lvl,msg,p1,p2,p3,p4,p5,p6,p7,p8)
#endif
+#define DUMPVAL(x) tracef(#x "=0x%x " _ (int)(x));
+#define DUMPVALN(x) tracef(#x "=0x%x\n" _ (int)(x));
-/* main entry for compression */
-EXTERN void jpeg_compress PP((compress_info_ptr cinfo));
-
-/* default parameter setup for compression */
-EXTERN void j_c_defaults PP((compress_info_ptr cinfo, int quality,
- boolean force_baseline));
-EXTERN void j_monochrome_default PP((compress_info_ptr cinfo));
-EXTERN void j_set_quality PP((compress_info_ptr cinfo, int quality,
- boolean force_baseline));
-
-/* main entry for decompression */
-EXTERN void jpeg_decompress PP((decompress_info_ptr cinfo));
-
-/* default parameter setup for decompression */
-EXTERN void j_d_defaults PP((decompress_info_ptr cinfo,
- boolean standard_buffering));
-
-/* forward DCT */
-EXTERN void j_fwd_dct PP((DCTBLOCK data));
-/* inverse DCT */
-EXTERN void j_rev_dct PP((DCTBLOCK data));
-
-/* utility routines in jutils.c */
-EXTERN long jround_up PP((long a, long b));
-EXTERN void jcopy_sample_rows PP((JSAMPARRAY input_array, int source_row,
- JSAMPARRAY output_array, int dest_row,
- int num_rows, long num_cols));
-EXTERN void jcopy_block_row PP((JBLOCKROW input_row, JBLOCKROW output_row,
- long num_blocks));
-EXTERN void jzero_far PP((void FAR * target, size_t bytestozero));
-
-/* method selection routines for compression modules */
-EXTERN void jselcpipeline PP((compress_info_ptr cinfo)); /* jcpipe.c */
-EXTERN void jselchuffman PP((compress_info_ptr cinfo)); /* jchuff.c */
-EXTERN void jselcarithmetic PP((compress_info_ptr cinfo)); /* jcarith.c */
-EXTERN void jselexpand PP((compress_info_ptr cinfo)); /* jcexpand.c */
-EXTERN void jselsubsample PP((compress_info_ptr cinfo)); /* jcsample.c */
-EXTERN void jselcmcu PP((compress_info_ptr cinfo)); /* jcmcu.c */
-EXTERN void jselccolor PP((compress_info_ptr cinfo)); /* jccolor.c */
-/* The user interface should call one of these to select input format: */
-EXTERN void jselrgif PP((compress_info_ptr cinfo)); /* jrdgif.c */
-EXTERN void jselrppm PP((compress_info_ptr cinfo)); /* jrdppm.c */
-EXTERN void jselrrle PP((compress_info_ptr cinfo)); /* jrdrle.c */
-EXTERN void jselrtarga PP((compress_info_ptr cinfo)); /* jrdtarga.c */
-/* and one of these to select output header format: */
-EXTERN void jselwjfif PP((compress_info_ptr cinfo)); /* jwrjfif.c */
-
-/* method selection routines for decompression modules */
-EXTERN void jseldpipeline PP((decompress_info_ptr cinfo)); /* jdpipe.c */
-EXTERN void jseldhuffman PP((decompress_info_ptr cinfo)); /* jdhuff.c */
-EXTERN void jseldarithmetic PP((decompress_info_ptr cinfo)); /* jdarith.c */
-EXTERN void jseldmcu PP((decompress_info_ptr cinfo)); /* jdmcu.c */
-EXTERN void jselbsmooth PP((decompress_info_ptr cinfo)); /* jbsmooth.c */
-EXTERN void jselunsubsample PP((decompress_info_ptr cinfo)); /* jdsample.c */
-EXTERN void jseldcolor PP((decompress_info_ptr cinfo)); /* jdcolor.c */
-EXTERN void jsel1quantize PP((decompress_info_ptr cinfo)); /* jquant1.c */
-EXTERN void jsel2quantize PP((decompress_info_ptr cinfo)); /* jquant2.c */
-/* The user interface should call one of these to select input format: */
-EXTERN void jselrjfif PP((decompress_info_ptr cinfo)); /* jrdjfif.c */
-/* and one of these to select output image format: */
-EXTERN void jselwgif PP((decompress_info_ptr cinfo)); /* jwrgif.c */
-EXTERN void jselwppm PP((decompress_info_ptr cinfo)); /* jwrppm.c */
-EXTERN void jselwrle PP((decompress_info_ptr cinfo)); /* jwrrle.c */
-EXTERN void jselwtarga PP((decompress_info_ptr cinfo)); /* jwrtarga.c */
-
-/* method selection routines for system-dependent modules */
-EXTERN void jselerror PP((external_methods_ptr emethods)); /* jerror.c */
-EXTERN void jselmemmgr PP((external_methods_ptr emethods)); /* jmemmgr.c */
-
+#ifdef EMBED
+ #define ERREXIT(emeth,msg) {tracef("Error:"); tracef(msg); newline(); EXIT}
+ #define ERREXIT1(emeth,msg,p1) {tracef("Error:"); tracef(msg _ p1); newline(); EXIT}
+ #define ERREXIT2(emeth,msg,p1,p2) {tracef("Error:"); tracef(msg _ p1 _ p2); newline(); EXIT}
+ #define ERREXIT3(emeth,msg,p1,p2,p3) {tracef("Error:"); tracef(msg _ p1 _ p2 _ p3); newline(); EXIT}
+ #define ERREXIT4(emeth,msg,p1,p2,p3,p4) {tracef("Error:"); tracef(msg _ p1 _ p2 _ p3 _ p4); newline(); EXIT}
+#else
+ #define ERREXIT(emeth,msg) {printf("Error:"); printf(msg); printf("\n"); exit(1);}
+ #define ERREXIT1(emeth,msg,p1) {printf("Error:"); printf(msg,p1); printf("\n"); exit(1);}
+ #define ERREXIT2(emeth,msg,p1,p2) {printf("Error:"); printf(msg,p1,p2); printf("\n"); exit(1);}
+ #define ERREXIT3(emeth,msg,p1,p2,p3) {printf("Error:"); printf(msg,p1,p2,p3); printf("\n"); exit(1);}
+ #define ERREXIT4(emeth,msg,p1,p2,p3,p4) {printf("Error:"); printf(msg,p1,p2,p3,p4); printf("\n"); exit(1);}
+#endif
/* We assume that right shift corresponds to signed division by 2 with
* rounding towards minus infinity. This is correct for typical "arithmetic
diff -U 3 -H -b -B -d -p -r -N -- jpeg-5/jpeglib.h cvs/h/jpeglib
--- jpeg-5/jpeglib.h 1994-08-25 15:20:36.000000000 +0100
+++ cvs/h/jpeglib 1996-11-05 09:45:08.000000000 +0000
@@ -1,3 +1,20 @@
+/* This source code in this file is licensed to You by Castle Technology
+ * Limited ("Castle") and its licensors on contractual terms and conditions
+ * ("Licence") which entitle you freely to modify and/or to distribute this
+ * source code subject to Your compliance with the terms of the Licence.
+ *
+ * This source code has been made available to You without any warranties
+ * whatsoever. Consequently, Your use, modification and distribution of this
+ * source code is entirely at Your own risk and neither Castle, its licensors
+ * nor any other person who has contributed to this source code shall be
+ * liable to You for any loss or damage which You may suffer as a result of
+ * Your use, modification or distribution of this source code.
+ *
+ * Full details of Your rights and obligations are set out in the Licence.
+ * You should have received a copy of the Licence with this source code file.
+ * If You have not received a copy, the text of the Licence is available
+ * online at www.castle-technology.co.uk/riscosbaselicence.htm
+ */
/*
* jpeglib.h
*
@@ -738,7 +755,6 @@ typedef JMETHOD(boolean, jpeg_marker_par
#define jpeg_stdio_src jStdSrc
#define jpeg_set_defaults jSetDefaults
#define jpeg_set_colorspace jSetColorspace
-#define jpeg_default_colorspace jDefColorspace
#define jpeg_set_quality jSetQuality
#define jpeg_set_linear_quality jSetLQuality
#define jpeg_add_quant_table jAddQuantTable
@@ -787,7 +803,6 @@ EXTERN void jpeg_set_defaults JPP((j_com
/* Compression parameter setup aids */
EXTERN void jpeg_set_colorspace JPP((j_compress_ptr cinfo,
J_COLOR_SPACE colorspace));
-EXTERN void jpeg_default_colorspace JPP((j_compress_ptr cinfo));
EXTERN void jpeg_set_quality JPP((j_compress_ptr cinfo, int quality,
boolean force_baseline));
EXTERN void jpeg_set_linear_quality JPP((j_compress_ptr cinfo,
diff -U 3 -H -b -B -d -p -r -N -- jpeg-3/jrdjfif.c cvs/c/jrdjfif
--- jpeg-3/jrdjfif.c 1992-01-17 23:28:05.000000000 +0000
+++ cvs/c/jrdjfif 1996-11-05 09:45:03.000000000 +0000
@@ -1,3 +1,20 @@
+/* This source code in this file is licensed to You by Castle Technology
+ * Limited ("Castle") and its licensors on contractual terms and conditions
+ * ("Licence") which entitle you freely to modify and/or to distribute this
+ * source code subject to Your compliance with the terms of the Licence.
+ *
+ * This source code has been made available to You without any warranties
+ * whatsoever. Consequently, Your use, modification and distribution of this
+ * source code is entirely at Your own risk and neither Castle, its licensors
+ * nor any other person who has contributed to this source code shall be
+ * liable to You for any loss or damage which You may suffer as a result of
+ * Your use, modification or distribution of this source code.
+ *
+ * Full details of Your rights and obligations are set out in the Licence.
+ * You should have received a copy of the Licence with this source code file.
+ * If You have not received a copy, the text of the Licence is available
+ * online at www.castle-technology.co.uk/riscosbaselicence.htm
+ */
/*
* jrdjfif.c
*
@@ -24,6 +41,8 @@
* These routines are invoked via the methods read_file_header,
* read_scan_header, read_jpeg_data, read_scan_trailer, and read_file_trailer.
*/
+#undef FILE_
+#define FILE_ (20000)
#include "jinclude.h"
@@ -85,37 +104,6 @@ typedef enum { /* JPEG marker codes */
/*
- * Reload the input buffer after it's been emptied, and return the next byte.
- * This is exported for direct use by the entropy decoder.
- * See the JGETC macro for calling conditions.
- *
- * For this header control module, read_jpeg_data is supplied by the
- * user interface. However, header formats that require random access
- * to the input file would need to supply their own code. This code is
- * left here to indicate what is required.
- */
-
-#if 0 /* not needed in this module */
-
-METHODDEF int
-read_jpeg_data (decompress_info_ptr cinfo)
-{
- cinfo->next_input_byte = cinfo->input_buffer + MIN_UNGET;
-
- cinfo->bytes_in_buffer = (int) JFREAD(cinfo->input_file,
- cinfo->next_input_byte,
- JPEG_BUF_SIZE);
-
- if (cinfo->bytes_in_buffer <= 0)
- ERREXIT(cinfo->emethods, "Unexpected EOF in JPEG file");
-
- return JGETC(cinfo);
-}
-
-#endif
-
-
-/*
* Routines to parse JPEG markers & save away the useful info.
*/
@@ -196,8 +184,10 @@ get_dht (decompress_info_ptr cinfo)
if (index < 0 || index >= NUM_HUFF_TBLS)
ERREXIT1(cinfo->emethods, "Bogus DHT index %d", index);
+#if 0
if (*htblptr == NULL)
- *htblptr = (HUFF_TBL *) (*cinfo->emethods->alloc_small) (SIZEOF(HUFF_TBL));
+ *htblptr = (HUFF_TBL *) malloc (SIZEOF(HUFF_TBL));
+#endif
memcpy((void *) (*htblptr)->bits, (void *) bits,
SIZEOF((*htblptr)->bits));
@@ -262,9 +252,11 @@ get_dqt (decompress_info_ptr cinfo)
if (n >= NUM_QUANT_TBLS)
ERREXIT1(cinfo->emethods, "Bogus table number %d", n);
+#if 0
if (cinfo->quant_tbl_ptrs[n] == NULL)
cinfo->quant_tbl_ptrs[n] = (QUANT_TBL_PTR)
- (*cinfo->emethods->alloc_small) (SIZEOF(QUANT_TBL));
+ malloc (SIZEOF(QUANT_TBL));
+#endif
quant_ptr = cinfo->quant_tbl_ptrs[n];
for (i = 0; i < DCTSIZE2; i++) {
@@ -394,8 +386,14 @@ get_sof (decompress_info_ptr cinfo, int
if (length != (cinfo->num_components * 3 + 8))
ERREXIT(cinfo->emethods, "Bogus SOF length");
- cinfo->comp_info = (jpeg_component_info *) (*cinfo->emethods->alloc_small)
+#if RISCOS
+ if (cinfo->num_components > 3)
+ ERREXIT(cinfo->emethods, "Too many colour components");
+ /* cinfo->comp_info set up already */
+#else
+ cinfo->comp_info = (jpeg_component_info *) malloc
(cinfo->num_components * SIZEOF(jpeg_component_info));
+#endif
for (ci = 0; ci < cinfo->num_components; ci++) {
compptr = &cinfo->comp_info[ci];
@@ -693,6 +691,7 @@ read_scan_header (decompress_info_ptr ci
}
+#if 0
/*
* Finish up after a compressed scan (series of read_jpeg_data calls);
* prepare for another read_scan_header call.
@@ -703,8 +702,9 @@ read_scan_trailer (decompress_info_ptr c
{
/* no work needed */
}
+#endif
-
+#if 0
/*
* Finish up at the end of the file.
*/
@@ -714,8 +714,10 @@ read_file_trailer (decompress_info_ptr c
{
/* no work needed */
}
+#endif
+#ifndef RISCOS
/*
* The method selection routine for standard JPEG header reading.
* Note that this must be called by the user interface before calling
@@ -737,4 +739,5 @@ jselrjfif (decompress_info_ptr cinfo)
cinfo->methods->read_file_trailer = read_file_trailer;
}
+#endif
#endif /* JFIF_SUPPORTED */
diff -U 3 -H -b -B -d -p -r -N -- jpeg-4/jrevdct.c cvs/c/jrevdct4
--- jpeg-4/jrevdct.c 1992-11-11 02:27:59.000000000 +0000
+++ cvs/c/jrevdct4 1996-11-05 09:45:03.000000000 +0000
@@ -1,3 +1,20 @@
+/* This source code in this file is licensed to You by Castle Technology
+ * Limited ("Castle") and its licensors on contractual terms and conditions
+ * ("Licence") which entitle you freely to modify and/or to distribute this
+ * source code subject to Your compliance with the terms of the Licence.
+ *
+ * This source code has been made available to You without any warranties
+ * whatsoever. Consequently, Your use, modification and distribution of this
+ * source code is entirely at Your own risk and neither Castle, its licensors
+ * nor any other person who has contributed to this source code shall be
+ * liable to You for any loss or damage which You may suffer as a result of
+ * Your use, modification or distribution of this source code.
+ *
+ * Full details of Your rights and obligations are set out in the Licence.
+ * You should have received a copy of the Licence with this source code file.
+ * If You have not received a copy, the text of the Licence is available
+ * online at www.castle-technology.co.uk/riscosbaselicence.htm
+ */
/*
* jrevdct.c
*
@@ -17,6 +34,10 @@
* multiplication; this allows a very simple and accurate implementation in
* scaled fixed-point arithmetic, with a minimal number of shifts.
*/
+#undef FILE_
+#define FILE_ (30000)
+/* This version has been updated to include gathering of statistics,
+for tuning other implementations. */
#include "jinclude.h"
@@ -66,8 +87,10 @@
*/
#ifdef EIGHT_BIT_SAMPLES
-#define CONST_BITS 13
-#define PASS1_BITS 2
+/* #define CONST_BITS 13 */
+/* #define PASS1_BITS 2 */
+#define CONST_BITS 8
+#define PASS1_BITS 8
#else
#define CONST_BITS 13
#define PASS1_BITS 1 /* lose a little precision to avoid overflow */
@@ -122,7 +145,14 @@
* the fudge factor is correct for either sign of X.
*/
-#define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
+/* special case for if we're trying to reduce precision and speed things ups */
+#if PASS1_BITS == CONST_BITS
+ #define DESCALE1(x,n) (x)
+ #define DESCALE(x,n) (x)
+#else
+ #define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
+ #define DESCALE1 DESCALE
+#endif
/* Multiply an INT32 variable by an INT32 constant to yield an INT32 result.
* For 8-bit samples with the recommended scaling, all the variable
@@ -135,26 +165,60 @@
* NB: for 12-bit samples, a full 32-bit multiplication will be needed.
*/
-#ifdef EIGHT_BIT_SAMPLES
-#ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
-#define MULTIPLY(var,const) (((INT16) (var)) * ((INT16) (const)))
-#endif
-#ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */
-#define MULTIPLY(var,const) (((INT16) (var)) * ((INT32) (const)))
-#endif
+#ifndef RISCOS
+ #ifdef EIGHT_BIT_SAMPLES
+ #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
+ #define MULTIPLY(var,const) (((INT16) (var)) * ((INT16) (const)))
+ #endif
+ #ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */
+ #define MULTIPLY(var,const) (((INT16) (var)) * ((INT32) (const)))
+ #endif
+ #endif
#endif
#ifndef MULTIPLY /* default definition */
#define MULTIPLY(var,const) ((var) * (const))
#endif
+#ifdef STATS
+static int how_many(int a, int b, int c, int d, int e, int f, int g, int h)
+/* How many of these 8 numbers are nonzero? */
+{
+ int i = 0;
+ if (a) i++;
+ if (b) i++;
+ if (c) i++;
+ if (d) i++;
+ if (e) i++;
+ if (f) i++;
+ if (g) i++;
+ if (h) i++;
+ return i;
+}
+
+static int how_many_row(DCTELEM *p, int size)
+{
+ return how_many( p[0] , p[1*size], p[2*size], p[3*size],
+ p[4*size], p[5*size], p[6*size], p[7*size]);
+}
+
+#endif
/*
* Perform the inverse DCT on one block of coefficients.
*/
GLOBAL void
-j_rev_dct (DCTBLOCK data)
+j_rev_dct (decompress_info_ptr cinfo, DCTBLOCK data, int count)
+/*
+ * NB in order to make the assembler equivalent more efficient, this routine
+ * now places its output at data-1, in row order. This is done as an
+ * entirely separate final pass.
+ *
+ * The output values are also unscaled, so you need to add 0x40000 and
+ * shift right by 19.
+ *
+ */
{
INT32 tmp0, tmp1, tmp2, tmp3;
INT32 tmp10, tmp11, tmp12, tmp13;
@@ -163,6 +227,10 @@ j_rev_dct (DCTBLOCK data)
int rowctr;
SHIFT_TEMPS
+ for (; count > 0; count--, data = (DCTELEM*)data + DCTSIZE2) {
+
+ IFSTATS(cinfo->stats.n_jblocks++;)
+
/* Pass 1: process rows. */
/* Note results are scaled up by sqrt(8) compared to a true IDCT; */
/* furthermore, we scale the results by 2**PASS1_BITS. */
@@ -178,11 +246,17 @@ j_rev_dct (DCTBLOCK data)
* row DCT calculations can be simplified this way.
*/
+ #ifdef STATS
+ cinfo->stats.n_lines_thismany_nonzero_coeffs_pass1[how_many_row(dataptr, 1)]++;
+ #endif
+
if ((dataptr[1] | dataptr[2] | dataptr[3] | dataptr[4] |
dataptr[5] | dataptr[6] | dataptr[7]) == 0) {
/* AC terms all zero */
- DCTELEM dcval = (DCTELEM) (dataptr[0] << PASS1_BITS);
+ DCTELEM dcval;
+ if (0 != (dcval = (DCTELEM) (dataptr[0] << PASS1_BITS)))
+ {
dataptr[0] = dcval;
dataptr[1] = dcval;
dataptr[2] = dcval;
@@ -191,11 +265,33 @@ j_rev_dct (DCTBLOCK data)
dataptr[5] = dcval;
dataptr[6] = dcval;
dataptr[7] = dcval;
+ }
+
+ #ifdef STATS
+ cinfo->stats.n_pass1_ac_zero++;
+ if (dcval == 0) cinfo->stats.n_pass1_ac_dc_zero++;
+ #endif
dataptr += DCTSIZE; /* advance pointer to next row */
continue;
}
+ #ifdef STATS
+ cinfo->stats.n_pass1_ac_nonzero++;
+ if (0 == how_many(0,0,0,0,dataptr[0],dataptr[2],dataptr[4],dataptr[6])) cinfo->stats.n_pass1_even_zero++;
+ if (0 == how_many(0,0,0,0,dataptr[1],dataptr[3],dataptr[5],dataptr[7])) cinfo->stats.n_pass1_odd_zero++;
+ else cinfo->stats.n_pass1_odd_nonzero++;
+
+ /* Look for cases where all the high frequency coeffs are zero */
+ {
+ int i;
+ for (i = DCTSIZE-1; i >= 0; i--) if (dataptr[i] != 0) break;
+ cinfo->stats.higher_coeff_all_zero[i]++;
+ }
+ #endif
+
+ /* printf("n "); */
+
/* Even part: reverse the even part of the forward DCT. */
/* The rotator is sqrt(2)*c(-6). */
@@ -248,14 +344,14 @@ j_rev_dct (DCTBLOCK data)
/* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
- dataptr[0] = (DCTELEM) DESCALE(tmp10 + tmp3, CONST_BITS-PASS1_BITS);
- dataptr[7] = (DCTELEM) DESCALE(tmp10 - tmp3, CONST_BITS-PASS1_BITS);
- dataptr[1] = (DCTELEM) DESCALE(tmp11 + tmp2, CONST_BITS-PASS1_BITS);
- dataptr[6] = (DCTELEM) DESCALE(tmp11 - tmp2, CONST_BITS-PASS1_BITS);
- dataptr[2] = (DCTELEM) DESCALE(tmp12 + tmp1, CONST_BITS-PASS1_BITS);
- dataptr[5] = (DCTELEM) DESCALE(tmp12 - tmp1, CONST_BITS-PASS1_BITS);
- dataptr[3] = (DCTELEM) DESCALE(tmp13 + tmp0, CONST_BITS-PASS1_BITS);
- dataptr[4] = (DCTELEM) DESCALE(tmp13 - tmp0, CONST_BITS-PASS1_BITS);
+ dataptr[0] = (DCTELEM) DESCALE1(tmp10 + tmp3, CONST_BITS-PASS1_BITS);
+ dataptr[7] = (DCTELEM) DESCALE1(tmp10 - tmp3, CONST_BITS-PASS1_BITS);
+ dataptr[1] = (DCTELEM) DESCALE1(tmp11 + tmp2, CONST_BITS-PASS1_BITS);
+ dataptr[6] = (DCTELEM) DESCALE1(tmp11 - tmp2, CONST_BITS-PASS1_BITS);
+ dataptr[2] = (DCTELEM) DESCALE1(tmp12 + tmp1, CONST_BITS-PASS1_BITS);
+ dataptr[5] = (DCTELEM) DESCALE1(tmp12 - tmp1, CONST_BITS-PASS1_BITS);
+ dataptr[3] = (DCTELEM) DESCALE1(tmp13 + tmp0, CONST_BITS-PASS1_BITS);
+ dataptr[4] = (DCTELEM) DESCALE1(tmp13 - tmp0, CONST_BITS-PASS1_BITS);
dataptr += DCTSIZE; /* advance pointer to next row */
}
@@ -274,7 +370,10 @@ j_rev_dct (DCTBLOCK data)
* may be commented out.
*/
-#ifndef NO_ZERO_COLUMN_TEST
+ IFSTATS(cinfo->stats.n_lines_thismany_nonzero_coeffs_pass2[how_many_row(dataptr, DCTSIZE)]++;)
+
+ /* #ifndef NO_ZERO_COLUMN_TEST */
+ #if 0
if ((dataptr[DCTSIZE*1] | dataptr[DCTSIZE*2] | dataptr[DCTSIZE*3] |
dataptr[DCTSIZE*4] | dataptr[DCTSIZE*5] | dataptr[DCTSIZE*6] |
dataptr[DCTSIZE*7]) == 0) {
@@ -290,10 +389,12 @@ j_rev_dct (DCTBLOCK data)
dataptr[DCTSIZE*6] = dcval;
dataptr[DCTSIZE*7] = dcval;
+ /* printf("z2 "); */
+
dataptr++; /* advance pointer to next column */
continue;
}
-#endif
+ #endif
/* Even part: reverse the even part of the forward DCT. */
/* The rotator is sqrt(2)*c(-6). */
@@ -366,4 +467,19 @@ j_rev_dct (DCTBLOCK data)
dataptr++; /* advance pointer to next column */
}
+
+ /* Final pass to place output in an order compatible with the
+ assembler equivalent. */
+ dataptr = data;
+ {
+ int *inptr = dataptr;
+ int *outptr = inptr - 64;
+ int col;
+ int row;
+
+ for (row = 0; row < 8; row++)
+ for (col = 0; col < 8; col++)
+ outptr[row + 8 * col] = inptr[row * 8 + col];
+ }
+ }
}
Doc/JPEG/README_v3 0 → 100644
View file @ 864c4703
The Independent JPEG Group's JPEG software
==========================================
README for release 3 of 17-Mar-92
==================================
This distribution contains the third official release of the Independent JPEG
Group's free JPEG software. You are welcome to redistribute this software and
to use it for any purpose, subject to the conditions under LEGAL ISSUES, below.
For installation instructions, see file SETUP; for usage instructions, see
file USAGE (or the cjpeg.1 and djpeg.1 manual pages).
This software is still undergoing revision. Updated versions may be obtained
by FTP or UUCP to UUNET and other archive sites; see ARCHIVE LOCATIONS below
for details.
If you intend to become a serious user of this software, please contact
jpeg-info@uunet.uu.net to be added to our electronic mailing list. Then
you'll be notified of updates and have a chance to participate in discussions,
etc.
This software is the work of Tom Lane, Philip Gladstone, Luis Ortiz,
Lee Crocker, Ge' Weijers, and other members of the Independent JPEG Group.
DISCLAIMER
==========
THIS SOFTWARE IS NOT COMPLETE NOR FULLY DEBUGGED. It is not guaranteed to be
useful for anything, nor to be compatible with subsequent releases, nor to be
an accurate implementation of the JPEG standard. (See LEGAL ISSUES for even
more disclaimers.)
Please report any problems with this software to jpeg-info@uunet.uu.net.
WHAT'S HERE
===========
This distribution contains C software to implement JPEG image compression and
decompression. JPEG (pronounced "jay-peg") is a standardized compression
method for full-color and gray-scale images. JPEG is intended for
"real-world" scenes; cartoons and other non-realistic images are not its
strong suit. JPEG is lossy, meaning that the output image is not necessarily
identical to the input image. Hence you should not use JPEG if you have to
have identical output bits. However, on typical images of real-world scenes,
very good compression levels can be obtained with no visible change, and
amazingly high compression levels can be obtained if you can tolerate a
low-quality image. For more details, see the references, or just experiment
with various compression settings.
The software implements JPEG baseline and extended-sequential compression
processes. Provision is made for supporting all variants of these processes,
although some uncommon parameter settings aren't implemented yet. For legal
reasons, we are not distributing code for the arithmetic-coding process; see
LEGAL ISSUES. At present we have made no provision for supporting the
progressive, hierarchical, or lossless processes defined in the standard.
The present software is not far beyond the prototype stage. It does not
support all possible variants of the JPEG standard, and some functions have
rather slow and/or crude implementations. However, it is useful already.
The emphasis in designing this software has been on achieving portability and
flexibility, while also making it fast enough to be useful. We have not yet
undertaken serious performance measurement or tuning; we intend to do so in
the future.
This software can be used on several levels:
* As canned software for JPEG compression and decompression. Just edit the
Makefile and configuration files as needed (see file SETUP), compile and go.
Members of the Independent JPEG Group will improve the out-of-the-box
functionality and speed as time goes on.
* As the basis for other JPEG programs. For example, you could incorporate
the decompressor into a general image viewing package by replacing the
output module with write-to-screen functions. For an implementation on
specific hardware, you might want to replace some of the inner loops with
assembly code. For a non-command-line-driven system, you might want a
different user interface. (Members of the group will be producing Macintosh
and Amiga versions with more appropriate user interfaces, for example.)
* As a toolkit for experimentation with JPEG and JPEG-like algorithms. Most
of the individual decisions you might want to mess with are packaged up into
separate modules. For example, the details of color-space conversion and
subsampling techniques are each localized in one compressor and one
decompressor module. You'd probably also want to extend the user interface
to give you more detailed control over the JPEG compression parameters.
In particular, we welcome the use of this software as a component of commercial
products; no royalty is required.
ARCHIVE LOCATIONS
=================
The "official" archive site for this software is ftp.uu.net (Internet
address 137.39.1.9 or 192.48.96.9). The most recent released version can
always be found there in directory graphics/jpeg. This particular version
will be archived as jpegsrc.v3.tar.Z. If you are on the Internet, you can
retrieve files from UUNET by anonymous FTP. If you don't have FTP access,
UUNET's archives are also available via UUCP; contact postmaster@uunet.uu.net
for information on retrieving files that way.
Various other Internet sites maintain copies of the UUNET file, which may or
may not be up-to-date. In Europe, try nic.funet.fi (128.214.6.100; look in
directory pub/graphics/programs/jpeg).
You can also obtain this software from CompuServe, in the GRAPHSUPPORT forum
(GO PICS), library 10; this version will be file jpsrc3.zip.
If you are not reasonably handy at configuring and installing portable C
programs, you may have some difficulty installing this package. You may
prefer to obtain a pre-built executable version. A collection of pre-built
executables for various machines is currently available for anonymous FTP at
procyon.cis.ksu.edu (129.130.10.80 --- this number is due to change soon);
look under /pub/JPEG. The administrators of this system ask that FTP traffic
be limited to non-prime hours. For more information on this archive, please
contact Steve Davis (strat@cis.ksu.edu). This collection is not maintained by
the Independent JPEG Group, and programs in it may not be the latest version.
SUPPORTING SOFTWARE
===================
You will probably want Jef Poskanzer's PBMPLUS image software, which provides
many useful operations on PPM-format image files. In particular, it can
convert PPM images to and from a wide range of other formats. You can FTP
this free software from export.lcs.mit.edu (contrib/pbmplus*.tar.Z) or
ftp.ee.lbl.gov (pbmplus*.tar.Z). Unfortunately PBMPLUS is not nearly as
portable as the JPEG software is; you are likely to have difficulty making it
work on any non-Unix machine.
If you are using X Windows you might want to use the xv or xloadimage viewers
to save yourself the trouble of converting PPM to some other format. Both of
these can be found in the contrib directory at export.lcs.mit.edu. Actually,
xv version 2.00 and up incorporates our software and thus can read and write
JPEG files directly. (NOTE: since xv internally reduces all images to 8
bits/pixel, a JPEG file written by xv will not be very high quality; you may
also prefer xloadimage for viewing if you have a 24-bit display. Caveat user.)
For DOS machines, Lee Crocker's free Piclab program is a useful companion to
the JPEG software. The latest version, currently 1.91, is available by FTP
from SIMTEL20 and its various mirror sites, file <msdos.graphics>piclb191.zip.
CompuServe also has it, in the same library as the JPEG software.
SOFTWARE THAT'S NO HELP AT ALL
==============================
Handmade Software's shareware PC program GIF2JPG produces files that are
totally incompatible with our programs. They use a proprietary format that is
an amalgam of GIF and JPEG representations. However, you can force GIF2JPG
to produce compatible files with its -j switch, and their decompression
program JPG2GIF can read our files (at least ones produced with our default
option settings).
Unfortunately, many commercial JPEG implementations are also incompatible as
of this writing, especially programs released before summer 1991. The root of
the problem is that the ISO JPEG committee failed to specify a concrete file
format. Some vendors "filled in the blanks" on their own, creating
proprietary formats that no one else could read. (For example, none of the
early commercial JPEG implementations for the Macintosh were able to exchange
compressed files.)
The file format we have adopted is called JFIF (see REFERENCES). This format
has been agreed to by a number of major commercial JPEG vendors, and we expect
that it will become the de facto standard. JFIF is a minimal representation;
work is also going forward to incorporate JPEG compression into the TIFF
standard, for use in "high end" applications that need to record a lot of
additional data about an image. We intend to support JPEG-in-TIFF in the
future. We hope that these two formats will be sufficient and that other,
incompatible JPEG file formats will not proliferate.
Indeed, part of the reason for developing and releasing this free software is
to help force rapid convergence to de facto standards for JPEG file formats.
SUPPORT STANDARD, NON-PROPRIETARY FORMATS: demand JFIF or JPEG-in-TIFF!
USING JPEG AS A SUBROUTINE IN A LARGER PROGRAM
==============================================
You can readily incorporate the JPEG compression and decompression routines in
a larger program. The file example.c provides a skeleton of the interface
routines you'll need for this purpose. Essentially, you replace jcmain.c (for
compression) and/or jdmain.c (for decompression) with your own code. Note
that the fewer JPEG options you allow the user to twiddle, the less code you
need; all the default options are set up automatically. (Alternately, if you
know a lot about JPEG or have a special application, you may want to twiddle
the default options even more extensively than jcmain/jdmain do.)
Most likely, you will want the uncompressed image to come from memory (for
compression) or go to memory or the screen (for decompression). For this
purpose you must provide image reading or writing routines that match the
interface used by the image file I/O modules (jrdXXX or jwrXXX); again,
example.c shows a skeleton of what is required.
By default, any error detected inside the JPEG routines will cause a message
to be printed on stderr, followed by exit(). You can override this behavior
by supplying your own message-printing and/or error-exit routines; again,
example.c shows how.
Mechanics: we recommend you create libjpeg.a as shown in the Makefile, then
link that with your surrounding program. (If your linker is at all
reasonable, only the code you actually need will get loaded.) Include the
files jconfig.h and jpegdata.h in C files that need to call the JPEG routines.
CAUTION: some people have tried to compile JPEG and their surrounding code
with different compilers, e.g., cc for JPEG and c++ or gcc for the rest. This
is a Real Bad Move and you will deserve what happens to you if you try it.
(Hint: the parameter structures can get laid out differently with no warning.)
Read our "architecture" file for more info. If it seems to you that the
software structure doesn't accommodate what you want to do, please contact
the authors.
Beginning with version 3, we will endeavor to hold the interface described by
example.c constant, so that you can plug in updated versions of the JPEG code
just by recompiling. However, we can't guarantee this, especially if you
choose to twiddle any JPEG options not listed in example.c. Check the
CHANGELOG when installing any new version, and compare example.c against the
prior version. Recompile your calling software (don't just relink), as we may
add or subtract fields in the parameter structures.
REFERENCES
==========
The best and most readily available introduction to the JPEG compression
algorithm is Wallace's article in the April '91 CACM:
Wallace, Gregory K. "The JPEG Still Picture Compression Standard",
Communications of the ACM, April 1991 (vol. 34 no. 4), pp. 30-44.
(Adjacent articles in that issue discuss MPEG motion picture compression,
applications of JPEG, and related topics.) We highly recommend reading that
article before trying to understand the innards of any JPEG software.
If you don't have the CACM issue handy, a PostScript file containing a revised
version of the article is available at ftp.uu.net, graphics/jpeg/wallace.ps.Z.
The file (actually a preprint for an article to appear in IEEE Trans. Consumer
Electronics) omits the sample images that appeared in CACM, but it includes
corrections and some added material. Note: the Wallace article is copyright
ACM and IEEE, and it may not be used for commercial purposes.
For more detail about the JPEG standard you pretty much have to go to the
draft standard (which is not nearly as intelligible as Wallace's article).
The standard is not now available electronically; you must order a paper copy
through ISO. In the US, copies may be ordered from ANSI Sales at (212)
642-4900. The standard is divided into two parts: Part 1 is the actual
specification, and Part 2 covers compliance testing methods. The current
"committee draft" version of Part 1 is titled "Digital Compression and Coding
of Continuous-tone Still Images, Part 1: Requirements and guidelines" and has
document number ISO/IEC CD 10918-1. (The alternate number SC2 N2215 should
also be mentioned when ordering.) This draft is expected to be superseded by
the Draft International Standard version around the end of November 1991.
Ordering info will be the same as above, but replace "CD" with "DIS" in the
document number (alternate number not yet known). The committee draft of
Part 2 is expected to be available around the end of December 1991. It will
be titled "Digital Compression and Coding of Continuous-tone Still Images,
Part 2: Compliance testing" and will have document number ISO/IEC CD 10918-2
(alternate number not yet known).
The JPEG standard does not specify all details of an interchangeable file
format. For the omitted details we follow the "JFIF" conventions, revision
1.01. A copy of the JFIF spec is available from:
Literature Department
C-Cube Microsystems, Inc.
399A West Trimble Road
San Jose, CA 95131
(408) 944-6300
The same source can supply copies of the draft JPEG-in-TIFF documents
(Appendixes O and P to the TIFF spec). PostScript versions of these
documents can also be obtained by e-mail from the C-Cube mail server,
netlib@c3.pla.ca.us. Send the message "send jfif_ps from jpeg" to obtain the
JFIF document; "send app_o_ps from jpeg" and "send app_p_ps from jpeg" will
produce the TIFF documents. Send the message "help" if you have trouble.
If you want to understand this implementation, start by reading the
"architecture" documentation file. Please read "codingrules" if you want to
contribute any code.
LEGAL ISSUES
============
The authors make NO WARRANTY or representation, either express or implied,
with respect to this software, its quality, accuracy, merchantability, or
fitness for a particular purpose. This software is provided "AS IS", and you,
its user, assume the entire risk as to its quality and accuracy.
This software is copyright (C) 1991, 1992, Thomas G. Lane.
All Rights Reserved except as specified below.
Permission is hereby granted to use, copy, modify, and distribute this
software (or portions thereof) for any purpose, without fee, subject to these
conditions:
(1) If any part of the source code for this software is distributed, then this
README file must be included, with this copyright and no-warranty notice
unaltered; and any additions, deletions, or changes to the original files
must be clearly indicated in accompanying documentation.
(2) If only executable code is distributed, then the accompanying
documentation must state that "this software is based in part on the work of
the Independent JPEG Group".
(3) Permission for use of this software is granted only if the user accepts
full responsibility for any undesirable consequences; the authors accept
NO LIABILITY for damages of any kind.
Permission is NOT granted for the use of any author's name or author's company
name in advertising or publicity relating to this software or products derived
from it. This software may be referred to only as "the Independent JPEG
Group's software".
We specifically permit and encourage the use of this software as the basis of
commercial products, provided that all warranty or liability claims are
assumed by the product vendor.
ansi2knr.c is included in this distribution by permission of L. Peter Deutsch,
sole proprietor of its copyright holder, Aladdin Enterprises of Menlo Park, CA.
ansi2knr.c is NOT covered by the above copyright and conditions, but instead
by the usual distribution terms of the Free Software Foundation; principally,
that you must include source code if you redistribute it. (See the file
ansi2knr.c for full details.) However, since ansi2knr.c is not needed as part
of any product generated from the JPEG code, this does not limit you more than
the foregoing paragraphs do.
It appears that the arithmetic coding option of the JPEG spec is covered by
patents owned by IBM and AT&T, as well as a pending Japanese patent of
Mitsubishi. Hence arithmetic coding cannot legally be used without obtaining
one or more licenses. For this reason, support for arithmetic coding has been
removed from the free JPEG software. (Since arithmetic coding provides only a
marginal gain over the unpatented Huffman mode, it is unlikely that very many
people will choose to use it. If you do obtain the necessary licenses,
contact jpeg-info@uunet.uu.net for a copy of our arithmetic coding modules.)
So far as we are aware, there are no patent restrictions on the remaining
code.
We are required to state that
"The Graphics Interchange Format(c) is the Copyright property of
CompuServe Incorporated. GIF(sm) is a Service Mark property of
CompuServe Incorporated."
TO DO
=====
Many of the modules need fleshing out to provide more complete
implementations, or to provide faster paths for common cases.
Improving the speed will be the next big work item for the JPEG group.
We'd appreciate it if people would compile and check out the code on as wide a
variety of systems as possible, and report any portability problems
encountered (with solutions, if possible). Checks of file compatibility with
other JPEG implementations would also be of interest. Finally, we would
appreciate code profiles showing where the most time is spent, especially on
unusual systems.
Please send bug reports, offers of help, etc. to jpeg-info@uunet.uu.net.
Doc/JPEG/README_v4 0 → 100644
View file @ 864c4703
The Independent JPEG Group's JPEG software
==========================================
README for release 4 of 10-Dec-92
=================================
This distribution contains the fourth public release of the Independent JPEG
Group's free JPEG software. You are welcome to redistribute this software and
to use it for any purpose, subject to the conditions under LEGAL ISSUES, below.
For installation instructions, see file SETUP.
For usage instructions, see file USAGE (or the cjpeg.1 and djpeg.1 manual
pages; but USAGE contains a "hints" section not found in the manual pages).
Useful information can also be found in the JPEG FAQ (Frequently Asked
Questions) article; see ARCHIVE LOCATIONS below to obtain the FAQ article.
This software is still undergoing revision. Updated versions may be obtained
by FTP or UUCP to UUNET and other archive sites; see ARCHIVE LOCATIONS below
for details.
Serious users of this software (particularly those incorporating it into
larger programs) should contact jpeg-info@uunet.uu.net to be added to our
electronic mailing list. Mailing list members are notified of updates and
have a chance to participate in technical discussions, etc.
This software is the work of Tom Lane, Philip Gladstone, Luis Ortiz,
Lee Crocker, Ge' Weijers, and other members of the Independent JPEG Group.
DISCLAIMER
==========
THIS SOFTWARE IS NOT COMPLETE NOR FULLY DEBUGGED. It is not guaranteed to be
useful for anything, nor to be compatible with subsequent releases, nor to be
an accurate implementation of the JPEG standard. (See LEGAL ISSUES for even
more disclaimers.)
Despite that, we believe that this software is pretty good, and if you find
any problems with it, we'd like to know about them. Please report problems
by e-mail to jpeg-info@uunet.uu.net.
WHAT'S HERE
===========
This distribution contains C software to implement JPEG image compression and
decompression. JPEG (pronounced "jay-peg") is a standardized compression
method for full-color and gray-scale images. JPEG is intended for compressing
"real-world" scenes; cartoons and other non-realistic images are not its
strong suit. JPEG is lossy, meaning that the output image is not necessarily
identical to the input image. Hence you must not use JPEG if you have to have
identical output bits. However, on typical images of real-world scenes, very
good compression levels can be obtained with no visible change, and amazingly
high compression levels are possible if you can tolerate a low-quality image.
For more details, see the references, or just experiment with various
compression settings.
The software implements JPEG baseline and extended-sequential compression
processes. Provision is made for supporting all variants of these processes,
although some uncommon parameter settings aren't implemented yet. For legal
reasons, we are not distributing code for the arithmetic-coding process; see
LEGAL ISSUES. At present we have made no provision for supporting the
progressive, hierarchical, or lossless processes defined in the standard.
In order to support file conversion and viewing software, we have included
considerable functionality beyond the bare JPEG coding/decoding capability;
for example, the color quantization modules are not strictly part of JPEG
decoding, but they are essential for output to colormapped file formats or
colormapped displays. These extra functions can be compiled out if not
required for a particular application.
The emphasis in designing this software has been on achieving portability and
flexibility, while also making it fast enough to be useful. In particular,
the software is not intended to be read as a tutorial on JPEG. (See the
REFERENCES section for introductory material.) While we hope that the entire
package will someday be industrial-strength code, much remains to be done in
performance tuning and in improving the capabilities of individual modules.
This software can be used on several levels:
* As canned software for JPEG compression and decompression. Just edit the
Makefile and configuration files as needed (see file SETUP), compile and go.
Members of the Independent JPEG Group will improve the out-of-the-box
functionality and speed as time goes on.
* As the basis for other JPEG programs. For example, you could incorporate
the decompressor into a general image viewing package by replacing the
output module with write-to-screen functions. For an implementation on
specific hardware, you might want to replace some of the inner loops with
assembly code. For a non-command-line-driven system, you might want a
different user interface. (Members of the group will be producing Macintosh
and Amiga versions with more appropriate user interfaces, for example.)
* As a toolkit for experimentation with JPEG and JPEG-like algorithms. Most
of the individual decisions you might want to mess with are packaged up into
separate modules. For example, the details of color-space conversion and
subsampling techniques are each localized in one compressor and one
decompressor module. You'd probably also want to extend the user interface
to give you more detailed control over the JPEG compression parameters.
In particular, we welcome the use of this software as a component of commercial
products; no royalty is required.
ARCHIVE LOCATIONS
=================
The "official" archive site for this software is ftp.uu.net (Internet
address 137.39.1.9 or 192.48.96.9). The most recent released version can
always be found there in directory graphics/jpeg. This particular version
will be archived as jpegsrc.v4.tar.Z. If you are on the Internet, you can
retrieve files from UUNET by anonymous FTP. If you don't have FTP access,
UUNET's archives are also available via UUCP; contact postmaster@uunet.uu.net
for information on retrieving files that way.
Numerous Internet sites maintain copies of the UUNET files; in particular,
you can probably find a copy at any site that archives comp.sources.misc
submissions. However, only ftp.uu.net is guaranteed to have the latest
official version.
You can also obtain this software from CompuServe, in the GRAPHSUPPORT forum
(GO PICS), library 15; this version will be file jpsrc4.zip. Again,
CompuServe is not guaranteed to have the very latest version.
The JPEG FAQ (Frequently Asked Questions) article is a useful source of
general information about JPEG. It is updated constantly and therefore
is not included in this distribution. The FAQ is posted every two weeks
to Usenet newsgroups comp.graphics, news.answers, and other groups. You
can always obtain the latest version from the news.answers archive at
rtfm.mit.edu (18.172.1.27). By FTP, fetch /pub/usenet/news.answers/jpeg-faq.
If you don't have FTP, send e-mail to mail-server@rtfm.mit.edu with body
"send usenet/news.answers/jpeg-faq".
SUPPORTING SOFTWARE
===================
You will probably want Jef Poskanzer's PBMPLUS image software, which provides
many useful operations on PPM-format image files. In particular, it can
convert PPM images to and from a wide range of other formats. You can FTP
this free software from export.lcs.mit.edu (contrib/pbmplus*.tar.Z) or
ftp.ee.lbl.gov (pbmplus*.tar.Z). Unfortunately PBMPLUS is not nearly as
portable as the JPEG software is; you are likely to have difficulty making it
work on any non-Unix machine.
If you are using X Windows you might want to use the xv or xloadimage viewers
to save yourself the trouble of converting PPM to some other format. Both of
these can be found in the contrib directory at export.lcs.mit.edu. Actually,
xv version 2.00 and up incorporates our software and thus can read and write
JPEG files directly. (NOTE: since xv internally reduces all images to 8
bits/pixel, a JPEG file written by xv will not be very high quality; and xv
cannot fully exploit a 24-bit display. These problems are expected to go away
in the next xv release, planned for early 1993. In the meantime, use
xloadimage for 24-bit displays.)
For DOS machines, Lee Crocker's free Piclab program is a useful companion to
the JPEG software. The latest version, currently 1.91, is available by FTP
from SIMTEL20 and its various mirror sites, file <msdos.graphics>piclb191.zip.
CompuServe also has it, in the same library as the JPEG software.
SOFTWARE THAT'S NO HELP AT ALL
==============================
Handmade Software's shareware PC program GIF2JPG produces files that are
totally incompatible with our programs. They use a proprietary format that is
an amalgam of GIF and JPEG representations. However, you can force GIF2JPG
to produce compatible files with its -j switch, and their decompression
program JPG2GIF can read our files (at least ones produced with our default
option settings).
Some commercial JPEG implementations are also incompatible as of this writing,
especially programs released before summer 1991. The root of the problem is
that the ISO JPEG committee failed to specify a concrete file format. Some
vendors "filled in the blanks" on their own, creating proprietary formats that
no one else could read. (For example, none of the early commercial JPEG
implementations for the Macintosh were able to exchange compressed files.)
The file format we have adopted is called JFIF (see REFERENCES). This format
has been agreed to by a number of major commercial JPEG vendors, and we expect
that it will become the de facto standard. JFIF is a minimal representation;
work is also going forward to incorporate JPEG compression into the TIFF 6.0
standard, for use in "high end" applications that need to record a lot of
additional data about an image. We intend to support TIFF 6.0 in the future.
We hope that these two formats will be sufficient and that other, incompatible
JPEG file formats will not proliferate.
Indeed, part of the reason for developing and releasing this free software is
to help force rapid convergence to de facto standards for JPEG file formats.
SUPPORT STANDARD, NON-PROPRIETARY FORMATS: demand JFIF or TIFF 6.0!
USING JPEG AS A SUBROUTINE IN A LARGER PROGRAM
==============================================
You can readily incorporate the JPEG compression and decompression routines in
a larger program. The file example.c provides a skeleton of the interface
routines you'll need for this purpose. Essentially, you replace jcmain.c (for
compression) and/or jdmain.c (for decompression) with your own code. Note
that the fewer JPEG options you allow the user to twiddle, the less code you
need; all the default options are set up automatically. (Alternately, if you
know a lot about JPEG or have a special application, you may want to twiddle
the default options even more extensively than jcmain/jdmain do.)
Most likely, you will want the uncompressed image to come from memory (for
compression) or go to memory or the screen (for decompression). For this
purpose you must provide image reading or writing routines that match the
interface used by the image file I/O modules (jrdXXX or jwrXXX); again,
example.c shows a skeleton of what is required. In this situation, you
won't need any of the non-JPEG image file I/O modules used by cjpeg and djpeg.
By default, any error detected inside the JPEG routines will cause a message
to be printed on stderr, followed by exit(). You can override this behavior
by supplying your own message-printing and/or error-exit routines; again,
example.c shows how.
We recommend you create libjpeg.a as shown in the Makefile, then link that
with your surrounding program. (If your linker is at all reasonable, only the
code you actually need will get loaded.) Include the files jconfig.h and
jpegdata.h in C files that need to call the JPEG routines.
CAUTION: some people have tried to compile JPEG and their surrounding code
with different compilers, e.g., cc for JPEG and c++ or gcc for the rest. This
is a Real Bad Move and you will deserve what happens to you if you try it.
(Hint: the parameter structures can get laid out differently with no warning.)
Read our "architecture" file for more info. If it seems to you that the
software structure doesn't accommodate what you want to do, please contact
the authors.
Beginning with version 3, we will endeavor to hold the interface described by
example.c constant, so that you can plug in updated versions of the JPEG code
just by recompiling. However, we can't guarantee this, especially if you
choose to twiddle any JPEG options not listed in example.c. Check the
CHANGELOG when installing any new version, and compare example.c against the
prior version. Recompile your calling software (don't just relink), as we may
add or subtract fields in the parameter structures.
REFERENCES
==========
We highly recommend reading one or more of these references before trying to
understand the innards of any JPEG software.
The best short technical introduction to the JPEG compression algorithm is
Wallace, Gregory K. "The JPEG Still Picture Compression Standard",
Communications of the ACM, April 1991 (vol. 34 no. 4), pp. 30-44.
(Adjacent articles in that issue discuss MPEG motion picture compression,
applications of JPEG, and related topics.) If you don't have the CACM issue
handy, a PostScript file containing a revised version of the article is
available at ftp.uu.net, graphics/jpeg/wallace.ps.Z. The file (actually a
preprint for an article to appear in IEEE Trans. Consumer Electronics) omits
the sample images that appeared in CACM, but it includes corrections and some
added material. Note: the Wallace article is copyright ACM and IEEE, and it
may not be used for commercial purposes.
A somewhat less technical, more leisurely introduction to JPEG can be found in
"The Data Compression Book" by Mark Nelson, published by M&T Books (Redwood
City, CA), 1991, ISBN 1-55851-216-0. This book provides good explanations and
example C code for a multitude of compression methods including JPEG. It is
an excellent source if you are comfortable reading C code but don't know much
about data compression in general. The book's JPEG sample code is far from
industrial-strength, but when you are ready to look at a full implementation,
you've got one here...
A new textbook about JPEG is "JPEG Still Image Data Compression Standard" by
William B. Pennebaker and Joan L. Mitchell, published by Van Nostrand
Reinhold, 1993, ISBN 0-442-01272-1. Price US$59.95. This book includes the
complete text of the ISO JPEG standards (DIS 10918-1 and draft DIS 10918-2).
This is by far the most complete exposition of JPEG in existence, and I highly
recommend it. If you read the entire book, you will probably know more about
JPEG than I do.
The JPEG standard itself is not available electronically; you must order a
paper copy through ISO. (Unless you are concerned about having a certified
official copy, I recommend buying the Pennebaker and Mitchell book instead;
it's much cheaper and includes a great deal of useful explanatory material.)
In the US, copies of the standard may be ordered from ANSI Sales at (212)
642-4900. It's not cheap: as of 1992, Part 1 is $95 and Part 2 is $47, plus
7% shipping/handling. The standard is divided into two parts, Part 1 being
the actual specification, while Part 2 covers compliance testing methods.
As of early 1992, Part 1 has Draft International Standard status. It is
titled "Digital Compression and Coding of Continuous-tone Still Images, Part
1: Requirements and guidelines" and has document number ISO/IEC DIS 10918-1.
Part 2 is still at Committee Draft status. It is titled "Digital Compression
and Coding of Continuous-tone Still Images, Part 2: Compliance testing" and
has document number ISO/IEC CD 10918-2. (NOTE: I'm told that the final
version of Part 2 will differ considerably from the CD draft.)
The JPEG standard does not specify all details of an interchangeable file
format. For the omitted details we follow the "JFIF" conventions, revision
1.02. A copy of the JFIF spec is available from:
Literature Department
C-Cube Microsystems, Inc.
399A West Trimble Road
San Jose, CA 95131
(408) 944-6300
A PostScript version of this document is available at ftp.uu.net, file
graphics/jpeg/jfif.ps.Z. It can also be obtained by e-mail from the C-Cube
mail server, netlib@c3.pla.ca.us. Send the message "send jfif_ps from jpeg"
to the server to obtain the JFIF document; send the message "help" if you have
trouble.
The TIFF 6.0 file format specification can be obtained by FTP from sgi.com
(192.48.153.1), file graphics/tiff/TIFF6.ps.Z; or you can order a printed copy
from Aldus Corp. at (206) 628-6593. It should be noted that the TIFF 6.0 spec
of 3-June-92 has a number of serious problems in its JPEG features. A
clarification note will probably be needed to ensure that TIFF JPEG files are
compatible across different implementations. The IJG does not intend to
support TIFF 6.0 until these problems are resolved.
If you want to understand this implementation, start by reading the
"architecture" documentation file. Please read "codingrules" if you want to
contribute any code.
LEGAL ISSUES
============
The authors make NO WARRANTY or representation, either express or implied,
with respect to this software, its quality, accuracy, merchantability, or
fitness for a particular purpose. This software is provided "AS IS", and you,
its user, assume the entire risk as to its quality and accuracy.
This software is copyright (C) 1991, 1992, Thomas G. Lane.
All Rights Reserved except as specified below.
Permission is hereby granted to use, copy, modify, and distribute this
software (or portions thereof) for any purpose, without fee, subject to these
conditions:
(1) If any part of the source code for this software is distributed, then this
README file must be included, with this copyright and no-warranty notice
unaltered; and any additions, deletions, or changes to the original files
must be clearly indicated in accompanying documentation.
(2) If only executable code is distributed, then the accompanying
documentation must state that "this software is based in part on the work of
the Independent JPEG Group".
(3) Permission for use of this software is granted only if the user accepts
full responsibility for any undesirable consequences; the authors accept
NO LIABILITY for damages of any kind.
Permission is NOT granted for the use of any IJG author's name or company name
in advertising or publicity relating to this software or products derived from
it. This software may be referred to only as "the Independent JPEG Group's
software".
We specifically permit and encourage the use of this software as the basis of
commercial products, provided that all warranty or liability claims are
assumed by the product vendor.
ansi2knr.c is included in this distribution by permission of L. Peter Deutsch,
sole proprietor of its copyright holder, Aladdin Enterprises of Menlo Park, CA.
ansi2knr.c is NOT covered by the above copyright and conditions, but instead
by the usual distribution terms of the Free Software Foundation; principally,
that you must include source code if you redistribute it. (See the file
ansi2knr.c for full details.) However, since ansi2knr.c is not needed as part
of any program generated from the JPEG code, this does not limit you more than
the foregoing paragraphs do.
It appears that the arithmetic coding option of the JPEG spec is covered by
patents owned by IBM and AT&T, as well as a pending Japanese patent of
Mitsubishi. Hence arithmetic coding cannot legally be used without obtaining
one or more licenses. For this reason, support for arithmetic coding has been
removed from the free JPEG software. (Since arithmetic coding provides only a
marginal gain over the unpatented Huffman mode, it is unlikely that very many
implementors will support it. If you do obtain the necessary licenses,
contact jpeg-info@uunet.uu.net for a copy of our arithmetic coding modules.)
So far as we are aware, there are no patent restrictions on the remaining
code.
We are required to state that
"The Graphics Interchange Format(c) is the Copyright property of
CompuServe Incorporated. GIF(sm) is a Service Mark property of
CompuServe Incorporated."
TO DO
=====
The next major release will probably be a significant rewrite to allow use of
this code in conjunction with Sam Leffler's free TIFF library (assuming the
bugs in the TIFF 6.0 specification get resolved).
Many of the modules need fleshing out to provide more complete
implementations, or to provide faster paths for common cases.
Speeding things up is still high on our priority list.
We'd appreciate it if people would compile and check out the code on as wide a
variety of systems as possible, and report any portability problems
encountered (with solutions, if possible). Checks of file compatibility with
other JPEG implementations would also be of interest. Finally, we would
appreciate code profiles showing where the most time is spent, especially on
unusual systems.
Please send bug reports, offers of help, etc. to jpeg-info@uunet.uu.net.
Doc/JPEG/README_v5 0 → 100644
View file @ 864c4703
The Independent JPEG Group's JPEG software
==========================================
README for release 5 of 24-Sep-94
=================================
This distribution contains the fifth public release of the Independent JPEG
Group's free JPEG software. You are welcome to redistribute this software and
to use it for any purpose, subject to the conditions under LEGAL ISSUES, below.
Serious users of this software (particularly those incorporating it into
larger programs) should contact jpeg-info@uunet.uu.net to be added to our
electronic mailing list. Mailing list members are notified of updates and
have a chance to participate in technical discussions, etc.
This software is the work of Tom Lane, Philip Gladstone, Luis Ortiz, Jim
Boucher, Lee Crocker, George Phillips, Davide Rossi, Ge' Weijers, and other
members of the Independent JPEG Group.
IJG is not associated with the official ISO JPEG standards committee.
DOCUMENTATION ROADMAP
=====================
This file contains the following sections:
OVERVIEW General description of JPEG and the IJG software.
LEGAL ISSUES Copyright, lack of warranty, terms of distribution.
REFERENCES Where to learn more about JPEG.
ARCHIVE LOCATIONS Where to find newer versions of this software.
RELATED SOFTWARE Other stuff you should get.
FILE FORMAT WARS Software *not* to get.
TO DO Plans for future IJG releases.
Other documentation files in the distribution are:
User documentation:
install.doc How to configure and install the IJG software.
usage.doc Usage instructions for cjpeg, djpeg, rdjpgcom, wrjpgcom.
*.1 Unix-style man pages for programs (same info as usage.doc).
change.log Version-to-version change highlights.
Programmer and internal documentation:
libjpeg.doc How to use the JPEG library in your own programs.
example.c Sample code for calling the JPEG library.
structure.doc Overview of the JPEG library's internal structure.
filelist.doc Road map of IJG files.
coderules.doc Coding style rules --- please read if you contribute code.
Please read at least the files install.doc and usage.doc. Useful information
can also be found in the JPEG FAQ (Frequently Asked Questions) article. See
ARCHIVE LOCATIONS below to find out where to obtain the FAQ article.
If you want to understand how the JPEG code works, we suggest reading one or
more of the REFERENCES, then looking at the documentation files (in roughly
the order listed) before diving into the code.
OVERVIEW
========
This package contains C software to implement JPEG image compression and
decompression. JPEG (pronounced "jay-peg") is a standardized compression
method for full-color and gray-scale images. JPEG is intended for compressing
"real-world" scenes; cartoons and other non-realistic images are not its
strong suit. JPEG is lossy, meaning that the output image is not necessarily
identical to the input image. Hence you must not use JPEG if you have to have
identical output bits. However, on typical images of real-world scenes, very
good compression levels can be obtained with no visible change, and amazingly
high compression levels are possible if you can tolerate a low-quality image.
For more details, see the references, or just experiment with various
compression settings.
We provide a set of library routines for reading and writing JPEG image files,
plus two simple applications "cjpeg" and "djpeg", which use the library to
perform conversion between JPEG and some other popular image file formats.
The library is intended to be reused in other applications.
This software implements JPEG baseline and extended-sequential compression
processes. Provision is made for supporting all variants of these processes,
although some uncommon parameter settings aren't implemented yet. For legal
reasons, we are not distributing code for the arithmetic-coding process; see
LEGAL ISSUES. At present we have made no provision for supporting the
progressive, hierarchical, or lossless processes defined in the standard.
(Support for progressive mode may be offered in a future release.)
In order to support file conversion and viewing software, we have included
considerable functionality beyond the bare JPEG coding/decoding capability;
for example, the color quantization modules are not strictly part of JPEG
decoding, but they are essential for output to colormapped file formats or
colormapped displays. These extra functions can be compiled out of the
library if not required for a particular application. We have also included
two simple applications for inserting and extracting textual comments in
JFIF files.
The emphasis in designing this software has been on achieving portability and
flexibility, while also making it fast enough to be useful. In particular,
the software is not intended to be read as a tutorial on JPEG. (See the
REFERENCES section for introductory material.) While we hope that the entire
package will someday be industrial-strength code, much remains to be done in
performance tuning and in improving the capabilities of individual modules.
We welcome the use of this software as a component of commercial products.
No royalty is required, but we do ask for an acknowledgement in product
documentation, as described under LEGAL ISSUES.
LEGAL ISSUES
============
In plain English:
1. We don't promise that this software works. (But if you find any bugs,
please let us know!)
2. You can use this software for whatever you want. You don't have to pay us.
3. You may not pretend that you wrote this software. If you use it in a
program, you must acknowledge somewhere in your documentation that
you've used the IJG code.
In legalese:
The authors make NO WARRANTY or representation, either express or implied,
with respect to this software, its quality, accuracy, merchantability, or
fitness for a particular purpose. This software is provided "AS IS", and you,
its user, assume the entire risk as to its quality and accuracy.
This software is copyright (C) 1991, 1992, 1993, 1994, Thomas G. Lane.
All Rights Reserved except as specified below.
Permission is hereby granted to use, copy, modify, and distribute this
software (or portions thereof) for any purpose, without fee, subject to these
conditions:
(1) If any part of the source code for this software is distributed, then this
README file must be included, with this copyright and no-warranty notice
unaltered; and any additions, deletions, or changes to the original files
must be clearly indicated in accompanying documentation.
(2) If only executable code is distributed, then the accompanying
documentation must state that "this software is based in part on the work of
the Independent JPEG Group".
(3) Permission for use of this software is granted only if the user accepts
full responsibility for any undesirable consequences; the authors accept
NO LIABILITY for damages of any kind.
These conditions apply to any software derived from or based on the IJG code,
not just to the unmodified library. If you use our work, you ought to
acknowledge us.
Permission is NOT granted for the use of any IJG author's name or company name
in advertising or publicity relating to this software or products derived from
it. This software may be referred to only as "the Independent JPEG Group's
software".
We specifically permit and encourage the use of this software as the basis of
commercial products, provided that all warranty or liability claims are
assumed by the product vendor.
ansi2knr.c is included in this distribution by permission of L. Peter Deutsch,
sole proprietor of its copyright holder, Aladdin Enterprises of Menlo Park, CA.
ansi2knr.c is NOT covered by the above copyright and conditions, but instead
by the usual distribution terms of the Free Software Foundation; principally,
that you must include source code if you redistribute it. (See the file
ansi2knr.c for full details.) However, since ansi2knr.c is not needed as part
of any program generated from the IJG code, this does not limit you more than
the foregoing paragraphs do.
The configuration script "configure" was produced by GNU Autoconf. Again,
the FSF copyright terms apply only to configure, not to the IJG code; and
again, that does not limit your use of the object code.
It appears that the arithmetic coding option of the JPEG spec is covered by
patents owned by IBM, AT&T, and Mitsubishi. Hence arithmetic coding cannot
legally be used without obtaining one or more licenses. For this reason,
support for arithmetic coding has been removed from the free JPEG software.
(Since arithmetic coding provides only a marginal gain over the unpatented
Huffman mode, it is unlikely that very many implementations will support it.)
So far as we are aware, there are no patent restrictions on the remaining
code.
We are required to state that
"The Graphics Interchange Format(c) is the Copyright property of
CompuServe Incorporated. GIF(sm) is a Service Mark property of
CompuServe Incorporated."
REFERENCES
==========
We highly recommend reading one or more of these references before trying to
understand the innards of the JPEG software.
The best short technical introduction to the JPEG compression algorithm is
Wallace, Gregory K. "The JPEG Still Picture Compression Standard",
Communications of the ACM, April 1991 (vol. 34 no. 4), pp. 30-44.
(Adjacent articles in that issue discuss MPEG motion picture compression,
applications of JPEG, and related topics.) If you don't have the CACM issue
handy, a PostScript file containing a revised version of Wallace's article is
available at ftp.uu.net, graphics/jpeg/wallace.ps.gz. The file (actually a
preprint for an article to appear in IEEE Trans. Consumer Electronics) omits
the sample images that appeared in CACM, but it includes corrections and some
added material. Note: the Wallace article is copyright ACM and IEEE, and it
may not be used for commercial purposes.
A somewhat less technical, more leisurely introduction to JPEG can be found in
"The Data Compression Book" by Mark Nelson, published by M&T Books (Redwood
City, CA), 1991, ISBN 1-55851-216-0. This book provides good explanations and
example C code for a multitude of compression methods including JPEG. It is
an excellent source if you are comfortable reading C code but don't know much
about data compression in general. The book's JPEG sample code is far from
industrial-strength, but when you are ready to look at a full implementation,
you've got one here...
The best full description of JPEG is the textbook "JPEG Still Image Data
Compression Standard" by William B. Pennebaker and Joan L. Mitchell, published
by Van Nostrand Reinhold, 1993, ISBN 0-442-01272-1. Price US$59.95, 638 pp.
The book includes the complete text of the ISO JPEG standards (DIS 10918-1
and draft DIS 10918-2). This is by far the most complete exposition of JPEG
in existence, and we highly recommend it.
The JPEG standard itself is not available electronically; you must order a
paper copy through ISO. (Unless you feel a need to own a certified official
copy, we recommend buying the Pennebaker and Mitchell book instead; it's much
cheaper and includes a great deal of useful explanatory material.) In the US,
copies of the standard may be ordered from ANSI Sales at (212) 642-4900, or
from Global Engineering Documents at (800) 854-7179. (ANSI doesn't take
credit card orders, but Global does.) It's not cheap: as of 1992, ANSI was
charging $95 for Part 1 and $47 for Part 2, plus 7% shipping/handling. The
standard is divided into two parts, Part 1 being the actual specification,
while Part 2 covers compliance testing methods. Part 1 is titled "Digital
Compression and Coding of Continuous-tone Still Images, Part 1: Requirements
and guidelines" and has document number ISO/IEC IS 10918-1. As of mid-1994,
Part 2 is still at Draft International Standard status. It is titled "Digital
Compression and Coding of Continuous-tone Still Images, Part 2: Compliance
testing" and has document number ISO/IEC DIS 10918-2. (The document number
will change to IS 10918-2 when final approval is obtained.) A Part 3,
covering extensions, is likely to appear in draft form in late 1994.
The JPEG standard does not specify all details of an interchangeable file
format. For the omitted details we follow the "JFIF" conventions, revision
1.02. A copy of the JFIF spec is available from:
Literature Department
C-Cube Microsystems, Inc.
1778 McCarthy Blvd.
Milpitas, CA 95035
phone (408) 944-6300, fax (408) 944-6314
A PostScript version of this document is available at ftp.uu.net, file
graphics/jpeg/jfif.ps.gz. It can also be obtained by e-mail from the C-Cube
mail server, netlib@c3.pla.ca.us. Send the message "send jfif_ps from jpeg"
to the server to obtain the JFIF document; send the message "help" if you have
trouble.
The TIFF 6.0 file format specification can be obtained by FTP from sgi.com
(192.48.153.1), file graphics/tiff/TIFF6.ps.Z; or you can order a printed copy
from Aldus Corp. at (206) 628-6593. It should be noted that the TIFF 6.0 spec
of 3-June-92 has a number of serious problems in its JPEG features. A
redesign effort is currently underway to correct these problems; it is
expected to result in a new, incompatible, spec. IJG intends to support the
corrected version of TIFF when the new spec is issued.
ARCHIVE LOCATIONS
=================
The "official" archive site for this software is ftp.uu.net (Internet
address 192.48.96.9). The most recent released version can always be found
there in directory graphics/jpeg. This particular version will be archived
as graphics/jpeg/jpegsrc.v5.tar.gz. If you are on the Internet, you
can retrieve files from ftp.uu.net by standard anonymous FTP. If you don't
have FTP access, UUNET's archives are also available via UUCP; contact
help@uunet.uu.net for information on retrieving files that way.
Numerous Internet sites maintain copies of the UUNET files; in particular,
you can probably find a copy at any site that archives comp.sources.misc
submissions. However, only ftp.uu.net is guaranteed to have the latest
official version.
You can also obtain this software from CompuServe, in the GRAPHSUPPORT forum
(GO GRAPHSUP); this version will be file jpsrc5.zip in library 15. Again,
CompuServe is not guaranteed to have the very latest version.
The JPEG FAQ (Frequently Asked Questions) article is a useful source of
general information about JPEG. It is updated constantly and therefore
is not included in this distribution. The FAQ is posted every two weeks
to Usenet newsgroups comp.graphics, news.answers, and other groups. You
can always obtain the latest version from the news.answers archive at
rtfm.mit.edu (18.181.0.24). By FTP, fetch /pub/usenet/news.answers/jpeg-faq.
If you don't have FTP, send e-mail to mail-server@rtfm.mit.edu with body
"send usenet/news.answers/jpeg-faq".
RELATED SOFTWARE
================
Numerous viewing and image manipulation programs now support JPEG. (Quite a
few of them use this library to do so.) The JPEG FAQ described above lists
some of the more popular free and shareware viewers, and tells where to
obtain them on Internet.
If you are on a Unix machine, we highly recommend Jef Poskanzer's free
PBMPLUS image software, which provides many useful operations on PPM-format
image files. In particular, it can convert PPM images to and from a wide
range of other formats. You can obtain this package by FTP from ftp.x.org
(contrib/pbmplus*.tar.Z) or ftp.ee.lbl.gov (pbmplus*.tar.Z). There is also
a newer update of this package called NETPBM, available from
wuarchive.wustl.edu under directory /graphics/graphics/packages/NetPBM/.
Unfortunately PBMPLUS/NETPBM is not nearly as portable as the IJG software
is; you are likely to have difficulty making it work on any non-Unix machine.
A different free JPEG implementation, written by the PVRG group at Stanford,
is available from havefun.stanford.edu in directory pub/jpeg. This program
is designed for research and experimentation rather than production use;
it is slower, harder to use, and less portable than the IJG code, but it
implements a larger subset of the JPEG standard. In particular, it supports
lossless JPEG.
FILE FORMAT WARS
================
Some JPEG programs produce files that are not compatible with our library.
The root of the problem is that the ISO JPEG committee failed to specify a
concrete file format. Some vendors "filled in the blanks" on their own,
creating proprietary formats that no one else could read. (For example, none
of the early commercial JPEG implementations for the Macintosh were able to
exchange compressed files.)
The file format we have adopted is called JFIF (see REFERENCES). This format
has been agreed to by a number of major commercial JPEG vendors, and it has
become the de facto standard. JFIF is a minimal or "low end" representation.
Work is also going forward to incorporate JPEG compression into the TIFF
standard, for use in "high end" applications that need to record a lot of
additional data about an image. We intend to support TIFF in the future.
We hope that these two formats will be sufficient and that other,
incompatible JPEG file formats will not proliferate.
Indeed, part of the reason for developing and releasing this free software is
to help force rapid convergence to de facto standards for JPEG file formats.
SUPPORT STANDARD, NON-PROPRIETARY FORMATS: demand JFIF or TIFF/JPEG!
TO DO
=====
In future versions, we are considering supporting progressive JPEG
compression, the upcoming JPEG Part 3 extensions, and other improvements.
As always, speeding things up is high on our priority list.
Please send bug reports, offers of help, etc. to jpeg-info@uunet.uu.net.
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