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Support arithmetic encoding and decoding

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git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@299 632fc199-4ca6-4c93-a231-07263d6284db
This commit is contained in:
DRC
2010-11-23 05:49:54 +00:00
parent 58842f9679 a4ecaacde6
commit 66f97e6820
24 changed files with 1953 additions and 80 deletions
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31
CMakeLists.txt
View File

@@ -90,13 +90,14 @@ include_directories(${CMAKE_CURRENT_BINARY_DIR} ${CMAKE_SOURCE_DIR})
# Targets
#
set(JPEG_SOURCES jcapimin.c jcapistd.c jccoefct.c jccolor.c jcdctmgr.c jchuff.c
jcinit.c jcmainct.c jcmarker.c jcmaster.c jcomapi.c jcparam.c jcphuff.c
jcprepct.c jcsample.c jctrans.c jdapimin.c jdapistd.c jdatadst.c jdatasrc.c
jdcoefct.c jdcolor.c jddctmgr.c jdhuff.c jdinput.c jdmainct.c jdmarker.c
jdmaster.c jdmerge.c jdphuff.c jdpostct.c jdsample.c jdtrans.c jerror.c
jfdctflt.c jfdctfst.c jfdctint.c jidctflt.c jidctfst.c jidctint.c jidctred.c
jquant1.c jquant2.c jutils.c jmemmgr.c jmemnobs.c)
set(JPEG_SOURCES jaricom.c jcapimin.c jcapistd.c jcarith.c jccoefct.c jccolor.c
jcdctmgr.c jchuff.c jcinit.c jcmainct.c jcmarker.c jcmaster.c jcomapi.c
jcparam.c jcphuff.c jcprepct.c jcsample.c jctrans.c jdapimin.c jdapistd.c
jdarith.c jdatadst.c jdatasrc.c jdcoefct.c jdcolor.c jddctmgr.c jdhuff.c
jdinput.c jdmainct.c jdmarker.c jdmaster.c jdmerge.c jdphuff.c jdpostct.c
jdsample.c jdtrans.c jerror.c jfdctflt.c jfdctfst.c jfdctint.c jidctflt.c
jidctfst.c jidctint.c jidctred.c jquant1.c jquant2.c jutils.c jmemmgr.c
jmemnobs.c)
if(WITH_SIMD)
add_definitions(-DWITH_SIMD)
@@ -201,6 +202,14 @@ add_test(cjpeg-prog sharedlib/cjpeg -dct int -progressive -outfile testoutp.jpg
add_test(cjpeg-prog-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgp.jpg testoutp.jpg)
add_test(jpegtran-prog sharedlib/jpegtran -outfile testoutt.jpg testoutp.jpg)
add_test(jpegtran-prog-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgint.jpg testoutt.jpg)
add_test(cjpeg-ari sharedlib/cjpeg -dct int -arithmetic -outfile testoutari.jpg ${CMAKE_SOURCE_DIR}/testorig.ppm)
add_test(cjpeg-ari-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgari.jpg testoutari.jpg)
add_test(djpeg-ari sharedlib/djpeg -dct int -fast -ppm -outfile testoutari.ppm ${CMAKE_SOURCE_DIR}/testimgari.jpg)
add_test(djpeg-ari-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgari.ppm testoutari.ppm)
add_test(jpegtran-toari sharedlib/jpegtran -arithmetic -outfile testouta.jpg testoutint.jpg)
add_test(jpegtran-toari-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgari.jpg testouta.jpg)
add_test(jpegtran-fromari sharedlib/jpegtran -outfile testouta.jpg testoutari.jpg)
add_test(jpegtran-fromari-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgint.jpg testouta.jpg)
add_test(jpegtran-crop sharedlib/jpegtran -crop 120x90+20+50 -transpose -perfect -outfile testoutcrop.jpg ${CMAKE_SOURCE_DIR}/testorig.jpg)
add_test(jpegtran-crop-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgcrop.jpg testoutcrop.jpg)
@@ -231,6 +240,14 @@ add_test(cjpeg-static-prog cjpeg-static -dct int -progressive -outfile testoutp.
add_test(cjpeg-static-prog-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgp.jpg testoutp.jpg)
add_test(jpegtran-static-prog jpegtran-static -outfile testoutt.jpg testoutp.jpg)
add_test(jpegtran-static-prog-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgint.jpg testoutt.jpg)
add_test(cjpeg-static-ari cjpeg-static -dct int -arithmetic -outfile testoutari.jpg ${CMAKE_SOURCE_DIR}/testorig.ppm)
add_test(cjpeg-static-ari-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgari.jpg testoutari.jpg)
add_test(djpeg-static-ari djpeg-static -dct int -fast -ppm -outfile testoutari.ppm ${CMAKE_SOURCE_DIR}/testimgari.jpg)
add_test(djpeg-static-ari-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgari.ppm testoutari.ppm)
add_test(jpegtran-static-toari jpegtran-static -arithmetic -outfile testouta.jpg testoutint.jpg)
add_test(jpegtran-static-toari-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgari.jpg testouta.jpg)
add_test(jpegtran-static-fromari jpegtran-static -outfile testouta.jpg testoutari.jpg)
add_test(jpegtran-static-fromari-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgint.jpg testouta.jpg)
add_test(jpegtran-static-crop jpegtran-static -crop 120x90+20+50 -transpose -perfect -outfile testoutcrop.jpg ${CMAKE_SOURCE_DIR}/testorig.jpg)
add_test(jpegtran-static-crop-cmp ${CMAKE_COMMAND} -E compare_files ${CMAKE_SOURCE_DIR}/testimgcrop.jpg testoutcrop.jpg)

2
ChangeLog.txt
View File

@@ -18,6 +18,8 @@ packages.
[6] All symbols in the libjpeg-turbo dynamic library are now versioned, even
when the library is built with libjpeg v6b emulation.
[7] Added arithmetic encoding and decoding support.
Significant changes since 1.0.0
===============================

73
Makefile.am
View File

@@ -7,14 +7,15 @@ nodist_include_HEADERS = jconfig.h
HDRS = jchuff.h jdct.h jdhuff.h jerror.h jinclude.h jmemsys.h jmorecfg.h \
jpegint.h jpeglib.h jversion.h jsimd.h jsimddct.h jpegcomp.h
libjpeg_la_SOURCES = $(HDRS) jcapimin.c jcapistd.c jccoefct.c jccolor.c \
jcdctmgr.c jchuff.c jcinit.c jcmainct.c jcmarker.c jcmaster.c \
jcomapi.c jcparam.c jcphuff.c jcprepct.c jcsample.c jctrans.c \
jdapimin.c jdapistd.c jdatadst.c jdatasrc.c jdcoefct.c jdcolor.c \
jddctmgr.c jdhuff.c jdinput.c jdmainct.c jdmarker.c jdmaster.c \
jdmerge.c jdphuff.c jdpostct.c jdsample.c jdtrans.c jerror.c \
jfdctflt.c jfdctfst.c jfdctint.c jidctflt.c jidctfst.c jidctint.c \
jidctred.c jquant1.c jquant2.c jutils.c jmemmgr.c jmemnobs.c
libjpeg_la_SOURCES = $(HDRS) jaricom.c jcapimin.c jcapistd.c jcarith.c \
jccoefct.c jccolor.c jcdctmgr.c jchuff.c jcinit.c jcmainct.c \
jcmarker.c jcmaster.c jcomapi.c jcparam.c jcphuff.c jcprepct.c \
jcsample.c jctrans.c jdapimin.c jdapistd.c jdarith.c \
jdatadst.c jdatasrc.c jdcoefct.c jdcolor.c jddctmgr.c jdhuff.c \
jdinput.c jdmainct.c jdmarker.c jdmaster.c jdmerge.c jdphuff.c \
jdpostct.c jdsample.c jdtrans.c jerror.c jfdctflt.c jfdctfst.c \
jfdctint.c jidctflt.c jidctfst.c jidctint.c jidctred.c \
jquant1.c jquant2.c jutils.c jmemmgr.c jmemnobs.c
libturbojpeg_la_SOURCES = $(libjpeg_la_SOURCES) turbojpegl.c turbojpeg.h \
turbojpeg-mapfile
@@ -103,49 +104,38 @@ dist-hook:
rm -rf `find $(distdir) -name .svn`
test: testclean all
./jpegut
./cjpeg -dct int -outfile testoutint.jpg $(srcdir)/testorig.ppm
cmp $(srcdir)/testimgint.jpg testoutint.jpg
./cjpeg -dct fast -opt -outfile testoutfst.jpg $(srcdir)/testorig.ppm
cmp $(srcdir)/testimgfst.jpg testoutfst.jpg
./cjpeg -dct float -outfile testoutflt.jpg $(srcdir)/testorig.ppm
if WITH_SIMD
test: testclean all
./jpegut
./cjpeg -dct int -outfile testoutint.jpg $(srcdir)/testorig.ppm
./cjpeg -dct fast -opt -outfile testoutfst.jpg $(srcdir)/testorig.ppm
./cjpeg -dct float -outfile testoutflt.jpg $(srcdir)/testorig.ppm
cmp $(srcdir)/testimgint.jpg testoutint.jpg
cmp $(srcdir)/testimgfst.jpg testoutfst.jpg
cmp $(srcdir)/testimgflt.jpg testoutflt.jpg
./djpeg -dct int -fast -ppm -outfile testoutint.ppm $(srcdir)/testorig.jpg
./djpeg -dct fast -ppm -outfile testoutfst.ppm $(srcdir)/testorig.jpg
./djpeg -dct float -ppm -outfile testoutflt.ppm $(srcdir)/testorig.jpg
cmp $(srcdir)/testimgint.ppm testoutint.ppm
cmp $(srcdir)/testimgfst.ppm testoutfst.ppm
cmp $(srcdir)/testimgflt.ppm testoutflt.ppm
./djpeg -dct int -bmp -colors 256 -outfile testout.bmp $(srcdir)/testorig.jpg
cmp $(srcdir)/testimg.bmp testout.bmp
./cjpeg -dct int -progressive -outfile testoutp.jpg $(srcdir)/testorig.ppm
cmp $(srcdir)/testimgp.jpg testoutp.jpg
./jpegtran -outfile testoutt.jpg testoutp.jpg
cmp $(srcdir)/testimgint.jpg testoutt.jpg
./jpegtran -crop 120x90+20+50 -transpose -perfect -outfile testoutcrop.jpg $(srcdir)/testorig.jpg
cmp $(srcdir)/testimgcrop.jpg testoutcrop.jpg
else
test: testclean all
./jpegut
./cjpeg -dct int -outfile testoutint.jpg $(srcdir)/testorig.ppm
./cjpeg -dct fast -opt -outfile testoutfst.jpg $(srcdir)/testorig.ppm
./cjpeg -dct float -outfile testoutflt.jpg $(srcdir)/testorig.ppm
cmp $(srcdir)/testimgint.jpg testoutint.jpg
cmp $(srcdir)/testimgfst.jpg testoutfst.jpg
cmp $(srcdir)/testimgflt-nosimd.jpg testoutflt.jpg
endif
./djpeg -dct int -fast -ppm -outfile testoutint.ppm $(srcdir)/testorig.jpg
./djpeg -dct fast -ppm -outfile testoutfst.ppm $(srcdir)/testorig.jpg
./djpeg -dct float -ppm -outfile testoutflt.ppm $(srcdir)/testorig.jpg
cmp $(srcdir)/testimgint.ppm testoutint.ppm
./djpeg -dct fast -ppm -outfile testoutfst.ppm $(srcdir)/testorig.jpg
cmp $(srcdir)/testimgfst.ppm testoutfst.ppm
./djpeg -dct float -ppm -outfile testoutflt.ppm $(srcdir)/testorig.jpg
if WITH_SIMD
cmp $(srcdir)/testimgflt.ppm testoutflt.ppm
else
cmp $(srcdir)/testorig.ppm testoutflt.ppm
endif
./djpeg -dct int -bmp -colors 256 -outfile testout.bmp $(srcdir)/testorig.jpg
cmp $(srcdir)/testimg.bmp testout.bmp
./cjpeg -dct int -arithmetic -outfile testoutari.jpg $(srcdir)/testorig.ppm
cmp $(srcdir)/testimgari.jpg testoutari.jpg
./djpeg -dct int -fast -ppm -outfile testoutari.ppm $(srcdir)/testimgari.jpg
cmp $(srcdir)/testimgari.ppm testoutari.ppm
./jpegtran -arithmetic -outfile testouta.jpg testoutint.jpg
cmp $(srcdir)/testimgari.jpg testouta.jpg
./jpegtran -outfile testouta.jpg testoutari.jpg
cmp $(srcdir)/testimgint.jpg testouta.jpg
./cjpeg -dct int -progressive -outfile testoutp.jpg $(srcdir)/testorig.ppm
cmp $(srcdir)/testimgp.jpg testoutp.jpg
./jpegtran -outfile testoutt.jpg testoutp.jpg
@@ -153,7 +143,6 @@ test: testclean all
./jpegtran -crop 120x90+20+50 -transpose -perfect -outfile testoutcrop.jpg $(srcdir)/testorig.jpg
cmp $(srcdir)/testimgcrop.jpg testoutcrop.jpg
endif
testclean:
rm -f testout*

14
README
View File

@@ -78,9 +78,8 @@ compressor.)
This software implements JPEG baseline, extended-sequential, and progressive
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
variants of JPEG; see LEGAL ISSUES. We have made no provision for supporting
the hierarchical or lossless processes defined in the standard.
We have made no provision for supporting the hierarchical or lossless
processes defined in the standard.
We provide a set of library routines for reading and writing JPEG image files,
plus two sample applications "cjpeg" and "djpeg", which use the library to
@@ -175,15 +174,6 @@ The same holds for its supporting scripts (config.guess, config.sub,
ltmain.sh). Another support script, install-sh, is copyright by X Consortium
but is also freely distributable.
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.
The IJG distribution formerly included code to read and write GIF files.
To avoid entanglement with the Unisys LZW patent, GIF reading support has
been removed altogether, and the GIF writer has been simplified to produce

3
change.log
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@@ -36,6 +36,9 @@ settings for luminance and chrominance (or in general, for every provided
quantization table slot).
New API function jpeg_default_qtables() and q_scale_factor array in library.
Support arithmetic entropy encoding and decoding.
Added files jaricom.c, jcarith.c, jdarith.c.
jpegtran has a new "lossless" cropping feature.
Implement -perfect option in jpegtran, new API function

8
cjpeg.1
View File

@@ -214,6 +214,12 @@ visibly blur the image, however.
.PP
Switches for wizards:
.TP
.B \-arithmetic
Use arithmetic coding.
.B Caution:
arithmetic coded JPEG is not yet widely implemented, so many decoders will be
unable to view an arithmetic coded JPEG file at all.
.TP
.B \-baseline
Force baseline-compatible quantization tables to be generated. This clamps
quantization values to 8 bits even at low quality settings. (This switch is
@@ -303,8 +309,6 @@ Communications of the ACM, April 1991 (vol. 34, no. 4), pp. 30-44.
.SH AUTHOR
Independent JPEG Group
.SH BUGS
Arithmetic coding is not supported for legal reasons.
.PP
Support for GIF input files was removed in cjpeg v6b due to concerns over
the Unisys LZW patent. Although this patent expired in 2006, cjpeg still
lacks GIF support, for these historical reasons. (Conversion of GIF files to

2
djpeg.1
View File

@@ -243,8 +243,6 @@ Communications of the ACM, April 1991 (vol. 34, no. 4), pp. 30-44.
.SH AUTHOR
Independent JPEG Group
.SH BUGS
Arithmetic coding is not supported for legal reasons.
.PP
To avoid the Unisys LZW patent,
.B djpeg
produces uncompressed GIF files. These are larger than they should be, but

4
filelist.txt
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@@ -74,6 +74,7 @@ jfdctfst.c Forward DCT using faster, less accurate integer method.
jfdctflt.c Forward DCT using floating-point arithmetic.
jchuff.c Huffman entropy coding for sequential JPEG.
jcphuff.c Huffman entropy coding for progressive JPEG.
jcarith.c Arithmetic entropy coding.
jcmarker.c JPEG marker writing.
jdatadst.c Data destination managers for memory and stdio output.
@@ -87,6 +88,7 @@ jdpostct.c Postprocessor buffer controller.
jdmarker.c JPEG marker reading.
jdhuff.c Huffman entropy decoding for sequential JPEG.
jdphuff.c Huffman entropy decoding for progressive JPEG.
jdarith.c Arithmetic entropy decoding.
jddctmgr.c IDCT manager (IDCT implementation selection & control).
jidctint.c Inverse DCT using slow-but-accurate integer method.
jidctfst.c Inverse DCT using faster, less accurate integer method.
@@ -102,6 +104,8 @@ jdatasrc.c Data source managers for memory and stdio input.
Support files for both compression and decompression:
jaricom.c Tables for common use in arithmetic entropy encoding and
decoding routines.
jerror.c Standard error handling routines (application replaceable).
jmemmgr.c System-independent (more or less) memory management code.
jutils.c Miscellaneous utility routines.

153
jaricom.c Normal file
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@@ -0,0 +1,153 @@
/*
* jaricom.c
*
* Developed 1997-2009 by Guido Vollbeding.
* 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 probability estimation tables for common use in
* arithmetic entropy encoding and decoding routines.
*
* This data represents Table D.2 in the JPEG spec (ISO/IEC IS 10918-1
* and CCITT Recommendation ITU-T T.81) and Table 24 in the JBIG spec
* (ISO/IEC IS 11544 and CCITT Recommendation ITU-T T.82).
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* The following #define specifies the packing of the four components
* into the compact INT32 representation.
* Note that this formula must match the actual arithmetic encoder
* and decoder implementation. The implementation has to be changed
* if this formula is changed.
* The current organization is leaned on Markus Kuhn's JBIG
* implementation (jbig_tab.c).
*/
#define V(i,a,b,c,d) (((INT32)a << 16) | ((INT32)c << 8) | ((INT32)d << 7) | b)
const INT32 jpeg_aritab[113+1] = {
/*
* Index, Qe_Value, Next_Index_LPS, Next_Index_MPS, Switch_MPS
*/
V( 0, 0x5a1d, 1, 1, 1 ),
V( 1, 0x2586, 14, 2, 0 ),
V( 2, 0x1114, 16, 3, 0 ),
V( 3, 0x080b, 18, 4, 0 ),
V( 4, 0x03d8, 20, 5, 0 ),
V( 5, 0x01da, 23, 6, 0 ),
V( 6, 0x00e5, 25, 7, 0 ),
V( 7, 0x006f, 28, 8, 0 ),
V( 8, 0x0036, 30, 9, 0 ),
V( 9, 0x001a, 33, 10, 0 ),
V( 10, 0x000d, 35, 11, 0 ),
V( 11, 0x0006, 9, 12, 0 ),
V( 12, 0x0003, 10, 13, 0 ),
V( 13, 0x0001, 12, 13, 0 ),
V( 14, 0x5a7f, 15, 15, 1 ),
V( 15, 0x3f25, 36, 16, 0 ),
V( 16, 0x2cf2, 38, 17, 0 ),
V( 17, 0x207c, 39, 18, 0 ),
V( 18, 0x17b9, 40, 19, 0 ),
V( 19, 0x1182, 42, 20, 0 ),
V( 20, 0x0cef, 43, 21, 0 ),
V( 21, 0x09a1, 45, 22, 0 ),
V( 22, 0x072f, 46, 23, 0 ),
V( 23, 0x055c, 48, 24, 0 ),
V( 24, 0x0406, 49, 25, 0 ),
V( 25, 0x0303, 51, 26, 0 ),
V( 26, 0x0240, 52, 27, 0 ),
V( 27, 0x01b1, 54, 28, 0 ),
V( 28, 0x0144, 56, 29, 0 ),
V( 29, 0x00f5, 57, 30, 0 ),
V( 30, 0x00b7, 59, 31, 0 ),
V( 31, 0x008a, 60, 32, 0 ),
V( 32, 0x0068, 62, 33, 0 ),
V( 33, 0x004e, 63, 34, 0 ),
V( 34, 0x003b, 32, 35, 0 ),
V( 35, 0x002c, 33, 9, 0 ),
V( 36, 0x5ae1, 37, 37, 1 ),
V( 37, 0x484c, 64, 38, 0 ),
V( 38, 0x3a0d, 65, 39, 0 ),
V( 39, 0x2ef1, 67, 40, 0 ),
V( 40, 0x261f, 68, 41, 0 ),
V( 41, 0x1f33, 69, 42, 0 ),
V( 42, 0x19a8, 70, 43, 0 ),
V( 43, 0x1518, 72, 44, 0 ),
V( 44, 0x1177, 73, 45, 0 ),
V( 45, 0x0e74, 74, 46, 0 ),
V( 46, 0x0bfb, 75, 47, 0 ),
V( 47, 0x09f8, 77, 48, 0 ),
V( 48, 0x0861, 78, 49, 0 ),
V( 49, 0x0706, 79, 50, 0 ),
V( 50, 0x05cd, 48, 51, 0 ),
V( 51, 0x04de, 50, 52, 0 ),
V( 52, 0x040f, 50, 53, 0 ),
V( 53, 0x0363, 51, 54, 0 ),
V( 54, 0x02d4, 52, 55, 0 ),
V( 55, 0x025c, 53, 56, 0 ),
V( 56, 0x01f8, 54, 57, 0 ),
V( 57, 0x01a4, 55, 58, 0 ),
V( 58, 0x0160, 56, 59, 0 ),
V( 59, 0x0125, 57, 60, 0 ),
V( 60, 0x00f6, 58, 61, 0 ),
V( 61, 0x00cb, 59, 62, 0 ),
V( 62, 0x00ab, 61, 63, 0 ),
V( 63, 0x008f, 61, 32, 0 ),
V( 64, 0x5b12, 65, 65, 1 ),
V( 65, 0x4d04, 80, 66, 0 ),
V( 66, 0x412c, 81, 67, 0 ),
V( 67, 0x37d8, 82, 68, 0 ),
V( 68, 0x2fe8, 83, 69, 0 ),
V( 69, 0x293c, 84, 70, 0 ),
V( 70, 0x2379, 86, 71, 0 ),
V( 71, 0x1edf, 87, 72, 0 ),
V( 72, 0x1aa9, 87, 73, 0 ),
V( 73, 0x174e, 72, 74, 0 ),
V( 74, 0x1424, 72, 75, 0 ),
V( 75, 0x119c, 74, 76, 0 ),
V( 76, 0x0f6b, 74, 77, 0 ),
V( 77, 0x0d51, 75, 78, 0 ),
V( 78, 0x0bb6, 77, 79, 0 ),
V( 79, 0x0a40, 77, 48, 0 ),
V( 80, 0x5832, 80, 81, 1 ),
V( 81, 0x4d1c, 88, 82, 0 ),
V( 82, 0x438e, 89, 83, 0 ),
V( 83, 0x3bdd, 90, 84, 0 ),
V( 84, 0x34ee, 91, 85, 0 ),
V( 85, 0x2eae, 92, 86, 0 ),
V( 86, 0x299a, 93, 87, 0 ),
V( 87, 0x2516, 86, 71, 0 ),
V( 88, 0x5570, 88, 89, 1 ),
V( 89, 0x4ca9, 95, 90, 0 ),
V( 90, 0x44d9, 96, 91, 0 ),
V( 91, 0x3e22, 97, 92, 0 ),
V( 92, 0x3824, 99, 93, 0 ),
V( 93, 0x32b4, 99, 94, 0 ),
V( 94, 0x2e17, 93, 86, 0 ),
V( 95, 0x56a8, 95, 96, 1 ),
V( 96, 0x4f46, 101, 97, 0 ),
V( 97, 0x47e5, 102, 98, 0 ),
V( 98, 0x41cf, 103, 99, 0 ),
V( 99, 0x3c3d, 104, 100, 0 ),
V( 100, 0x375e, 99, 93, 0 ),
V( 101, 0x5231, 105, 102, 0 ),
V( 102, 0x4c0f, 106, 103, 0 ),
V( 103, 0x4639, 107, 104, 0 ),
V( 104, 0x415e, 103, 99, 0 ),
V( 105, 0x5627, 105, 106, 1 ),
V( 106, 0x50e7, 108, 107, 0 ),
V( 107, 0x4b85, 109, 103, 0 ),
V( 108, 0x5597, 110, 109, 0 ),
V( 109, 0x504f, 111, 107, 0 ),
V( 110, 0x5a10, 110, 111, 1 ),
V( 111, 0x5522, 112, 109, 0 ),
V( 112, 0x59eb, 112, 111, 1 ),
/*
* This last entry is used for fixed probability estimate of 0.5
* as recommended in Section 10.3 Table 5 of ITU-T Rec. T.851.
*/
V( 113, 0x5a1d, 113, 113, 0 )
};

925
jcarith.c Normal file
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@@ -0,0 +1,925 @@
/*
* jcarith.c
*
* Developed 1997-2009 by Guido Vollbeding.
* 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 portable arithmetic entropy encoding routines for JPEG
* (implementing the ISO/IEC IS 10918-1 and CCITT Recommendation ITU-T T.81).
*
* Both sequential and progressive modes are supported in this single module.
*
* Suspension is not currently supported in this module.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* Expanded entropy encoder object for arithmetic encoding. */
typedef struct {
struct jpeg_entropy_encoder pub; /* public fields */
INT32 c; /* C register, base of coding interval, layout as in sec. D.1.3 */
INT32 a; /* A register, normalized size of coding interval */
INT32 sc; /* counter for stacked 0xFF values which might overflow */
INT32 zc; /* counter for pending 0x00 output values which might *
* be discarded at the end ("Pacman" termination) */
int ct; /* bit shift counter, determines when next byte will be written */
int buffer; /* buffer for most recent output byte != 0xFF */
int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
int dc_context[MAX_COMPS_IN_SCAN]; /* context index for DC conditioning */
unsigned int restarts_to_go; /* MCUs left in this restart interval */
int next_restart_num; /* next restart number to write (0-7) */
/* Pointers to statistics areas (these workspaces have image lifespan) */
unsigned char * dc_stats[NUM_ARITH_TBLS];
unsigned char * ac_stats[NUM_ARITH_TBLS];
/* Statistics bin for coding with fixed probability 0.5 */
unsigned char fixed_bin[4];
} arith_entropy_encoder;
typedef arith_entropy_encoder * arith_entropy_ptr;
/* The following two definitions specify the allocation chunk size
* for the statistics area.
* According to sections F.1.4.4.1.3 and F.1.4.4.2, we need at least
* 49 statistics bins for DC, and 245 statistics bins for AC coding.
*
* We use a compact representation with 1 byte per statistics bin,
* thus the numbers directly represent byte sizes.
* This 1 byte per statistics bin contains the meaning of the MPS
* (more probable symbol) in the highest bit (mask 0x80), and the
* index into the probability estimation state machine table
* in the lower bits (mask 0x7F).
*/
#define DC_STAT_BINS 64
#define AC_STAT_BINS 256
/* NOTE: Uncomment the following #define if you want to use the
* given formula for calculating the AC conditioning parameter Kx
* for spectral selection progressive coding in section G.1.3.2
* of the spec (Kx = Kmin + SRL (8 + Se - Kmin) 4).
* Although the spec and P&M authors claim that this "has proven
* to give good results for 8 bit precision samples", I'm not
* convinced yet that this is really beneficial.
* Early tests gave only very marginal compression enhancements
* (a few - around 5 or so - bytes even for very large files),
* which would turn out rather negative if we'd suppress the
* DAC (Define Arithmetic Conditioning) marker segments for
* the default parameters in the future.
* Note that currently the marker writing module emits 12-byte
* DAC segments for a full-component scan in a color image.
* This is not worth worrying about IMHO. However, since the
* spec defines the default values to be used if the tables
* are omitted (unlike Huffman tables, which are required
* anyway), one might optimize this behaviour in the future,
* and then it would be disadvantageous to use custom tables if
* they don't provide sufficient gain to exceed the DAC size.
*
* On the other hand, I'd consider it as a reasonable result
* that the conditioning has no significant influence on the
* compression performance. This means that the basic
* statistical model is already rather stable.
*
* Thus, at the moment, we use the default conditioning values
* anyway, and do not use the custom formula.
*
#define CALCULATE_SPECTRAL_CONDITIONING
*/
/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
* We assume that int right shift is unsigned if INT32 right shift is,
* which should be safe.
*/
#ifdef RIGHT_SHIFT_IS_UNSIGNED
#define ISHIFT_TEMPS int ishift_temp;
#define IRIGHT_SHIFT(x,shft) \
((ishift_temp = (x)) < 0 ? \
(ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
(ishift_temp >> (shft)))
#else
#define ISHIFT_TEMPS
#define IRIGHT_SHIFT(x,shft) ((x) >> (shft))
#endif
LOCAL(void)
emit_byte (int val, j_compress_ptr cinfo)
/* Write next output byte; we do not support suspension in this module. */
{
struct jpeg_destination_mgr * dest = cinfo->dest;
*dest->next_output_byte++ = (JOCTET) val;
if (--dest->free_in_buffer == 0)
if (! (*dest->empty_output_buffer) (cinfo))
ERREXIT(cinfo, JERR_CANT_SUSPEND);
}
/*
* Finish up at the end of an arithmetic-compressed scan.
*/
METHODDEF(void)
finish_pass (j_compress_ptr cinfo)
{
arith_entropy_ptr e = (arith_entropy_ptr) cinfo->entropy;
INT32 temp;
/* Section D.1.8: Termination of encoding */
/* Find the e->c in the coding interval with the largest
* number of trailing zero bits */
if ((temp = (e->a - 1 + e->c) & 0xFFFF0000L) < e->c)
e->c = temp + 0x8000L;
else
e->c = temp;
/* Send remaining bytes to output */
e->c <<= e->ct;
if (e->c & 0xF8000000L) {
/* One final overflow has to be handled */
if (e->buffer >= 0) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte(e->buffer + 1, cinfo);
if (e->buffer + 1 == 0xFF)
emit_byte(0x00, cinfo);
}
e->zc += e->sc; /* carry-over converts stacked 0xFF bytes to 0x00 */
e->sc = 0;
} else {
if (e->buffer == 0)
++e->zc;
else if (e->buffer >= 0) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte(e->buffer, cinfo);
}
if (e->sc) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
do {
emit_byte(0xFF, cinfo);
emit_byte(0x00, cinfo);
} while (--e->sc);
}
}
/* Output final bytes only if they are not 0x00 */
if (e->c & 0x7FFF800L) {
if (e->zc) /* output final pending zero bytes */
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte((e->c >> 19) & 0xFF, cinfo);
if (((e->c >> 19) & 0xFF) == 0xFF)
emit_byte(0x00, cinfo);
if (e->c & 0x7F800L) {
emit_byte((e->c >> 11) & 0xFF, cinfo);
if (((e->c >> 11) & 0xFF) == 0xFF)
emit_byte(0x00, cinfo);
}
}
}
/*
* The core arithmetic encoding routine (common in JPEG and JBIG).
* This needs to go as fast as possible.
* Machine-dependent optimization facilities
* are not utilized in this portable implementation.
* However, this code should be fairly efficient and
* may be a good base for further optimizations anyway.
*
* Parameter 'val' to be encoded may be 0 or 1 (binary decision).
*
* Note: I've added full "Pacman" termination support to the
* byte output routines, which is equivalent to the optional
* Discard_final_zeros procedure (Figure D.15) in the spec.
* Thus, we always produce the shortest possible output
* stream compliant to the spec (no trailing zero bytes,
* except for FF stuffing).
*
* I've also introduced a new scheme for accessing
* the probability estimation state machine table,
* derived from Markus Kuhn's JBIG implementation.
*/
LOCAL(void)
arith_encode (j_compress_ptr cinfo, unsigned char *st, int val)
{
register arith_entropy_ptr e = (arith_entropy_ptr) cinfo->entropy;
register unsigned char nl, nm;
register INT32 qe, temp;
register int sv;
/* Fetch values from our compact representation of Table D.2:
* Qe values and probability estimation state machine
*/
sv = *st;
qe = jpeg_aritab[sv & 0x7F]; /* => Qe_Value */
nl = qe & 0xFF; qe >>= 8; /* Next_Index_LPS + Switch_MPS */
nm = qe & 0xFF; qe >>= 8; /* Next_Index_MPS */
/* Encode & estimation procedures per sections D.1.4 & D.1.5 */
e->a -= qe;
if (val != (sv >> 7)) {
/* Encode the less probable symbol */
if (e->a >= qe) {
/* If the interval size (qe) for the less probable symbol (LPS)
* is larger than the interval size for the MPS, then exchange
* the two symbols for coding efficiency, otherwise code the LPS
* as usual: */
e->c += e->a;
e->a = qe;
}
*st = (sv & 0x80) ^ nl; /* Estimate_after_LPS */
} else {
/* Encode the more probable symbol */
if (e->a >= 0x8000L)
return; /* A >= 0x8000 -> ready, no renormalization required */
if (e->a < qe) {
/* If the interval size (qe) for the less probable symbol (LPS)
* is larger than the interval size for the MPS, then exchange
* the two symbols for coding efficiency: */
e->c += e->a;
e->a = qe;
}
*st = (sv & 0x80) ^ nm; /* Estimate_after_MPS */
}
/* Renormalization & data output per section D.1.6 */
do {
e->a <<= 1;
e->c <<= 1;
if (--e->ct == 0) {
/* Another byte is ready for output */
temp = e->c >> 19;
if (temp > 0xFF) {
/* Handle overflow over all stacked 0xFF bytes */
if (e->buffer >= 0) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte(e->buffer + 1, cinfo);
if (e->buffer + 1 == 0xFF)
emit_byte(0x00, cinfo);
}
e->zc += e->sc; /* carry-over converts stacked 0xFF bytes to 0x00 */
e->sc = 0;
/* Note: The 3 spacer bits in the C register guarantee
* that the new buffer byte can't be 0xFF here
* (see page 160 in the P&M JPEG book). */
e->buffer = temp & 0xFF; /* new output byte, might overflow later */
} else if (temp == 0xFF) {
++e->sc; /* stack 0xFF byte (which might overflow later) */
} else {
/* Output all stacked 0xFF bytes, they will not overflow any more */
if (e->buffer == 0)
++e->zc;
else if (e->buffer >= 0) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
emit_byte(e->buffer, cinfo);
}
if (e->sc) {
if (e->zc)
do emit_byte(0x00, cinfo);
while (--e->zc);
do {
emit_byte(0xFF, cinfo);
emit_byte(0x00, cinfo);
} while (--e->sc);
}
e->buffer = temp & 0xFF; /* new output byte (can still overflow) */
}
e->c &= 0x7FFFFL;
e->ct += 8;
}
} while (e->a < 0x8000L);
}
/*
* Emit a restart marker & resynchronize predictions.
*/
LOCAL(void)
emit_restart (j_compress_ptr cinfo, int restart_num)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
int ci;
jpeg_component_info * compptr;
finish_pass(cinfo);
emit_byte(0xFF, cinfo);
emit_byte(JPEG_RST0 + restart_num, cinfo);
/* Re-initialize statistics areas */
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* DC needs no table for refinement scan */
if (cinfo->progressive_mode == 0 || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
MEMZERO(entropy->dc_stats[compptr->dc_tbl_no], DC_STAT_BINS);
/* Reset DC predictions to 0 */
entropy->last_dc_val[ci] = 0;
entropy->dc_context[ci] = 0;
}
/* AC needs no table when not present */
if (cinfo->progressive_mode == 0 || cinfo->Se) {
MEMZERO(entropy->ac_stats[compptr->ac_tbl_no], AC_STAT_BINS);
}
}
/* Reset arithmetic encoding variables */
entropy->c = 0;
entropy->a = 0x10000L;
entropy->sc = 0;
entropy->zc = 0;
entropy->ct = 11;
entropy->buffer = -1; /* empty */
}
/*
* MCU encoding for DC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int blkn, ci, tbl;
int v, v2, m;
ISHIFT_TEMPS
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
tbl = cinfo->cur_comp_info[ci]->dc_tbl_no;
/* Compute the DC value after the required point transform by Al.
* This is simply an arithmetic right shift.
*/
m = IRIGHT_SHIFT((int) ((*block)[0]), cinfo->Al);
/* Sections F.1.4.1 & F.1.4.4.1: Encoding of DC coefficients */
/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
/* Figure F.4: Encode_DC_DIFF */
if ((v = m - entropy->last_dc_val[ci]) == 0) {
arith_encode(cinfo, st, 0);
entropy->dc_context[ci] = 0; /* zero diff category */
} else {
entropy->last_dc_val[ci] = m;
arith_encode(cinfo, st, 1);
/* Figure F.6: Encoding nonzero value v */
/* Figure F.7: Encoding the sign of v */
if (v > 0) {
arith_encode(cinfo, st + 1, 0); /* Table F.4: SS = S0 + 1 */
st += 2; /* Table F.4: SP = S0 + 2 */
entropy->dc_context[ci] = 4; /* small positive diff category */
} else {
v = -v;
arith_encode(cinfo, st + 1, 1); /* Table F.4: SS = S0 + 1 */
st += 3; /* Table F.4: SN = S0 + 3 */
entropy->dc_context[ci] = 8; /* small negative diff category */
}
/* Figure F.8: Encoding the magnitude category of v */
m = 0;
if (v -= 1) {
arith_encode(cinfo, st, 1);
m = 1;
v2 = v;
st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
while (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st += 1;
}
}
arith_encode(cinfo, st, 0);
/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
if (m < (int) ((1L << cinfo->arith_dc_L[tbl]) >> 1))
entropy->dc_context[ci] = 0; /* zero diff category */
else if (m > (int) ((1L << cinfo->arith_dc_U[tbl]) >> 1))
entropy->dc_context[ci] += 8; /* large diff category */
/* Figure F.9: Encoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
arith_encode(cinfo, st, (m & v) ? 1 : 0);
}
}
return TRUE;
}
/*
* MCU encoding for AC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int tbl, k, ke;
int v, v2, m;
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
/* Encode the MCU data block */
block = MCU_data[0];
tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
/* Sections F.1.4.2 & F.1.4.4.2: Encoding of AC coefficients */
/* Establish EOB (end-of-block) index */
for (ke = cinfo->Se; ke > 0; ke--)
/* We must apply the point transform by Al. For AC coefficients this
* is an integer division with rounding towards 0. To do this portably
* in C, we shift after obtaining the absolute value.
*/
if ((v = (*block)[jpeg_natural_order[ke]]) >= 0) {
if (v >>= cinfo->Al) break;
} else {
v = -v;
if (v >>= cinfo->Al) break;
}
/* Figure F.5: Encode_AC_Coefficients */
for (k = cinfo->Ss; k <= ke; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 0); /* EOB decision */
for (;;) {
if ((v = (*block)[jpeg_natural_order[k]]) >= 0) {
if (v >>= cinfo->Al) {
arith_encode(cinfo, st + 1, 1);
arith_encode(cinfo, entropy->fixed_bin, 0);
break;
}
} else {
v = -v;
if (v >>= cinfo->Al) {
arith_encode(cinfo, st + 1, 1);
arith_encode(cinfo, entropy->fixed_bin, 1);
break;
}
}
arith_encode(cinfo, st + 1, 0); st += 3; k++;
}
st += 2;
/* Figure F.8: Encoding the magnitude category of v */
m = 0;
if (v -= 1) {
arith_encode(cinfo, st, 1);
m = 1;
v2 = v;
if (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st = entropy->ac_stats[tbl] +
(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
while (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st += 1;
}
}
}
arith_encode(cinfo, st, 0);
/* Figure F.9: Encoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
arith_encode(cinfo, st, (m & v) ? 1 : 0);
}
/* Encode EOB decision only if k <= cinfo->Se */
if (k <= cinfo->Se) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 1);
}
return TRUE;
}
/*
* MCU encoding for DC successive approximation refinement scan.
*/
METHODDEF(boolean)
encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
unsigned char *st;
int Al, blkn;
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
st = entropy->fixed_bin; /* use fixed probability estimation */
Al = cinfo->Al;
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
/* We simply emit the Al'th bit of the DC coefficient value. */
arith_encode(cinfo, st, (MCU_data[blkn][0][0] >> Al) & 1);
}
return TRUE;
}
/*
* MCU encoding for AC successive approximation refinement scan.
*/
METHODDEF(boolean)
encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int tbl, k, ke, kex;
int v;
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
/* Encode the MCU data block */
block = MCU_data[0];
tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
/* Section G.1.3.3: Encoding of AC coefficients */
/* Establish EOB (end-of-block) index */
for (ke = cinfo->Se; ke > 0; ke--)
/* We must apply the point transform by Al. For AC coefficients this
* is an integer division with rounding towards 0. To do this portably
* in C, we shift after obtaining the absolute value.
*/
if ((v = (*block)[jpeg_natural_order[ke]]) >= 0) {
if (v >>= cinfo->Al) break;
} else {
v = -v;
if (v >>= cinfo->Al) break;
}
/* Establish EOBx (previous stage end-of-block) index */
for (kex = ke; kex > 0; kex--)
if ((v = (*block)[jpeg_natural_order[kex]]) >= 0) {
if (v >>= cinfo->Ah) break;
} else {
v = -v;
if (v >>= cinfo->Ah) break;
}
/* Figure G.10: Encode_AC_Coefficients_SA */
for (k = cinfo->Ss; k <= ke; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
if (k > kex)
arith_encode(cinfo, st, 0); /* EOB decision */
for (;;) {
if ((v = (*block)[jpeg_natural_order[k]]) >= 0) {
if (v >>= cinfo->Al) {
if (v >> 1) /* previously nonzero coef */
arith_encode(cinfo, st + 2, (v & 1));
else { /* newly nonzero coef */
arith_encode(cinfo, st + 1, 1);
arith_encode(cinfo, entropy->fixed_bin, 0);
}
break;
}
} else {
v = -v;
if (v >>= cinfo->Al) {
if (v >> 1) /* previously nonzero coef */
arith_encode(cinfo, st + 2, (v & 1));
else { /* newly nonzero coef */
arith_encode(cinfo, st + 1, 1);
arith_encode(cinfo, entropy->fixed_bin, 1);
}
break;
}
}
arith_encode(cinfo, st + 1, 0); st += 3; k++;
}
}
/* Encode EOB decision only if k <= cinfo->Se */
if (k <= cinfo->Se) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 1);
}
return TRUE;
}
/*
* Encode and output one MCU's worth of arithmetic-compressed coefficients.
*/
METHODDEF(boolean)
encode_mcu (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
jpeg_component_info * compptr;
JBLOCKROW block;
unsigned char *st;
int blkn, ci, tbl, k, ke;
int v, v2, m;
/* Emit restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0) {
emit_restart(cinfo, entropy->next_restart_num);
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num++;
entropy->next_restart_num &= 7;
}
entropy->restarts_to_go--;
}
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
compptr = cinfo->cur_comp_info[ci];
/* Sections F.1.4.1 & F.1.4.4.1: Encoding of DC coefficients */
tbl = compptr->dc_tbl_no;
/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
/* Figure F.4: Encode_DC_DIFF */
if ((v = (*block)[0] - entropy->last_dc_val[ci]) == 0) {
arith_encode(cinfo, st, 0);
entropy->dc_context[ci] = 0; /* zero diff category */
} else {
entropy->last_dc_val[ci] = (*block)[0];
arith_encode(cinfo, st, 1);
/* Figure F.6: Encoding nonzero value v */
/* Figure F.7: Encoding the sign of v */
if (v > 0) {
arith_encode(cinfo, st + 1, 0); /* Table F.4: SS = S0 + 1 */
st += 2; /* Table F.4: SP = S0 + 2 */
entropy->dc_context[ci] = 4; /* small positive diff category */
} else {
v = -v;
arith_encode(cinfo, st + 1, 1); /* Table F.4: SS = S0 + 1 */
st += 3; /* Table F.4: SN = S0 + 3 */
entropy->dc_context[ci] = 8; /* small negative diff category */
}
/* Figure F.8: Encoding the magnitude category of v */
m = 0;
if (v -= 1) {
arith_encode(cinfo, st, 1);
m = 1;
v2 = v;
st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
while (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st += 1;
}
}
arith_encode(cinfo, st, 0);
/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
if (m < (int) ((1L << cinfo->arith_dc_L[tbl]) >> 1))
entropy->dc_context[ci] = 0; /* zero diff category */
else if (m > (int) ((1L << cinfo->arith_dc_U[tbl]) >> 1))
entropy->dc_context[ci] += 8; /* large diff category */
/* Figure F.9: Encoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
arith_encode(cinfo, st, (m & v) ? 1 : 0);
}
/* Sections F.1.4.2 & F.1.4.4.2: Encoding of AC coefficients */
tbl = compptr->ac_tbl_no;
/* Establish EOB (end-of-block) index */
for (ke = DCTSIZE2 - 1; ke > 0; ke--)
if ((*block)[jpeg_natural_order[ke]]) break;
/* Figure F.5: Encode_AC_Coefficients */
for (k = 1; k <= ke; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 0); /* EOB decision */
while ((v = (*block)[jpeg_natural_order[k]]) == 0) {
arith_encode(cinfo, st + 1, 0); st += 3; k++;
}
arith_encode(cinfo, st + 1, 1);
/* Figure F.6: Encoding nonzero value v */
/* Figure F.7: Encoding the sign of v */
if (v > 0) {
arith_encode(cinfo, entropy->fixed_bin, 0);
} else {
v = -v;
arith_encode(cinfo, entropy->fixed_bin, 1);
}
st += 2;
/* Figure F.8: Encoding the magnitude category of v */
m = 0;
if (v -= 1) {
arith_encode(cinfo, st, 1);
m = 1;
v2 = v;
if (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st = entropy->ac_stats[tbl] +
(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
while (v2 >>= 1) {
arith_encode(cinfo, st, 1);
m <<= 1;
st += 1;
}
}
}
arith_encode(cinfo, st, 0);
/* Figure F.9: Encoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
arith_encode(cinfo, st, (m & v) ? 1 : 0);
}
/* Encode EOB decision only if k <= DCTSIZE2 - 1 */
if (k <= DCTSIZE2 - 1) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
arith_encode(cinfo, st, 1);
}
}
return TRUE;
}
/*
* Initialize for an arithmetic-compressed scan.
*/
METHODDEF(void)
start_pass (j_compress_ptr cinfo, boolean gather_statistics)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
int ci, tbl;
jpeg_component_info * compptr;
if (gather_statistics)
/* Make sure to avoid that in the master control logic!
* We are fully adaptive here and need no extra
* statistics gathering pass!
*/
ERREXIT(cinfo, JERR_NOT_COMPILED);
/* We assume jcmaster.c already validated the progressive scan parameters. */
/* Select execution routines */
if (cinfo->progressive_mode) {
if (cinfo->Ah == 0) {
if (cinfo->Ss == 0)
entropy->pub.encode_mcu = encode_mcu_DC_first;
else
entropy->pub.encode_mcu = encode_mcu_AC_first;
} else {
if (cinfo->Ss == 0)
entropy->pub.encode_mcu = encode_mcu_DC_refine;
else
entropy->pub.encode_mcu = encode_mcu_AC_refine;
}
} else
entropy->pub.encode_mcu = encode_mcu;
/* Allocate & initialize requested statistics areas */
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* DC needs no table for refinement scan */
if (cinfo->progressive_mode == 0 || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
tbl = compptr->dc_tbl_no;
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
if (entropy->dc_stats[tbl] == NULL)
entropy->dc_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, DC_STAT_BINS);
MEMZERO(entropy->dc_stats[tbl], DC_STAT_BINS);
/* Initialize DC predictions to 0 */
entropy->last_dc_val[ci] = 0;
entropy->dc_context[ci] = 0;
}
/* AC needs no table when not present */
if (cinfo->progressive_mode == 0 || cinfo->Se) {
tbl = compptr->ac_tbl_no;
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
if (entropy->ac_stats[tbl] == NULL)
entropy->ac_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, AC_STAT_BINS);
MEMZERO(entropy->ac_stats[tbl], AC_STAT_BINS);
#ifdef CALCULATE_SPECTRAL_CONDITIONING
if (cinfo->progressive_mode)
/* Section G.1.3.2: Set appropriate arithmetic conditioning value Kx */
cinfo->arith_ac_K[tbl] = cinfo->Ss + ((8 + cinfo->Se - cinfo->Ss) >> 4);
#endif
}
}
/* Initialize arithmetic encoding variables */
entropy->c = 0;
entropy->a = 0x10000L;
entropy->sc = 0;
entropy->zc = 0;
entropy->ct = 11;
entropy->buffer = -1; /* empty */
/* Initialize restart stuff */
entropy->restarts_to_go = cinfo->restart_interval;
entropy->next_restart_num = 0;
}
/*
* Module initialization routine for arithmetic entropy encoding.
*/
GLOBAL(void)
jinit_arith_encoder (j_compress_ptr cinfo)
{
arith_entropy_ptr entropy;
int i;
entropy = (arith_entropy_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(arith_entropy_encoder));
cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
entropy->pub.start_pass = start_pass;
entropy->pub.finish_pass = finish_pass;
/* Mark tables unallocated */
for (i = 0; i < NUM_ARITH_TBLS; i++) {
entropy->dc_stats[i] = NULL;
entropy->ac_stats[i] = NULL;
}
/* Initialize index for fixed probability estimation */
entropy->fixed_bin[0] = 113;
}

4
jcinit.c
View File

@@ -42,7 +42,11 @@ jinit_compress_master (j_compress_ptr cinfo)
jinit_forward_dct(cinfo);
/* Entropy encoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
#ifdef C_ARITH_CODING_SUPPORTED
jinit_arith_encoder(cinfo);
#else
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
#endif
} else {
if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED

4
jctrans.c
View File

@@ -174,7 +174,11 @@ transencode_master_selection (j_compress_ptr cinfo,
/* Entropy encoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
#ifdef C_ARITH_CODING_SUPPORTED
jinit_arith_encoder(cinfo);
#else
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
#endif
} else {
if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED

761
jdarith.c Normal file
View File

@@ -0,0 +1,761 @@
/*
* jdarith.c
*
* Developed 1997-2009 by Guido Vollbeding.
* 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 portable arithmetic entropy decoding routines for JPEG
* (implementing the ISO/IEC IS 10918-1 and CCITT Recommendation ITU-T T.81).
*
* Both sequential and progressive modes are supported in this single module.
*
* Suspension is not currently supported in this module.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* Expanded entropy decoder object for arithmetic decoding. */
typedef struct {
struct jpeg_entropy_decoder pub; /* public fields */
INT32 c; /* C register, base of coding interval + input bit buffer */
INT32 a; /* A register, normalized size of coding interval */
int ct; /* bit shift counter, # of bits left in bit buffer part of C */
/* init: ct = -16 */
/* run: ct = 0..7 */
/* error: ct = -1 */
int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
int dc_context[MAX_COMPS_IN_SCAN]; /* context index for DC conditioning */
unsigned int restarts_to_go; /* MCUs left in this restart interval */
/* Pointers to statistics areas (these workspaces have image lifespan) */
unsigned char * dc_stats[NUM_ARITH_TBLS];
unsigned char * ac_stats[NUM_ARITH_TBLS];
/* Statistics bin for coding with fixed probability 0.5 */
unsigned char fixed_bin[4];
} arith_entropy_decoder;
typedef arith_entropy_decoder * arith_entropy_ptr;
/* The following two definitions specify the allocation chunk size
* for the statistics area.
* According to sections F.1.4.4.1.3 and F.1.4.4.2, we need at least
* 49 statistics bins for DC, and 245 statistics bins for AC coding.
*
* We use a compact representation with 1 byte per statistics bin,
* thus the numbers directly represent byte sizes.
* This 1 byte per statistics bin contains the meaning of the MPS
* (more probable symbol) in the highest bit (mask 0x80), and the
* index into the probability estimation state machine table
* in the lower bits (mask 0x7F).
*/
#define DC_STAT_BINS 64
#define AC_STAT_BINS 256
LOCAL(int)
get_byte (j_decompress_ptr cinfo)
/* Read next input byte; we do not support suspension in this module. */
{
struct jpeg_source_mgr * src = cinfo->src;
if (src->bytes_in_buffer == 0)
if (! (*src->fill_input_buffer) (cinfo))
ERREXIT(cinfo, JERR_CANT_SUSPEND);
src->bytes_in_buffer--;
return GETJOCTET(*src->next_input_byte++);
}
/*
* The core arithmetic decoding routine (common in JPEG and JBIG).
* This needs to go as fast as possible.
* Machine-dependent optimization facilities
* are not utilized in this portable implementation.
* However, this code should be fairly efficient and
* may be a good base for further optimizations anyway.
*
* Return value is 0 or 1 (binary decision).
*
* Note: I've changed the handling of the code base & bit
* buffer register C compared to other implementations
* based on the standards layout & procedures.
* While it also contains both the actual base of the
* coding interval (16 bits) and the next-bits buffer,
* the cut-point between these two parts is floating
* (instead of fixed) with the bit shift counter CT.
* Thus, we also need only one (variable instead of
* fixed size) shift for the LPS/MPS decision, and
* we can get away with any renormalization update
* of C (except for new data insertion, of course).
*
* I've also introduced a new scheme for accessing
* the probability estimation state machine table,
* derived from Markus Kuhn's JBIG implementation.
*/
LOCAL(int)
arith_decode (j_decompress_ptr cinfo, unsigned char *st)
{
register arith_entropy_ptr e = (arith_entropy_ptr) cinfo->entropy;
register unsigned char nl, nm;
register INT32 qe, temp;
register int sv, data;
/* Renormalization & data input per section D.2.6 */
while (e->a < 0x8000L) {
if (--e->ct < 0) {
/* Need to fetch next data byte */
if (cinfo->unread_marker)
data = 0; /* stuff zero data */
else {
data = get_byte(cinfo); /* read next input byte */
if (data == 0xFF) { /* zero stuff or marker code */
do data = get_byte(cinfo);
while (data == 0xFF); /* swallow extra 0xFF bytes */
if (data == 0)
data = 0xFF; /* discard stuffed zero byte */
else {
/* Note: Different from the Huffman decoder, hitting
* a marker while processing the compressed data
* segment is legal in arithmetic coding.
* The convention is to supply zero data
* then until decoding is complete.
*/
cinfo->unread_marker = data;
data = 0;
}
}
}
e->c = (e->c << 8) | data; /* insert data into C register */
if ((e->ct += 8) < 0) /* update bit shift counter */
/* Need more initial bytes */
if (++e->ct == 0)
/* Got 2 initial bytes -> re-init A and exit loop */
e->a = 0x8000L; /* => e->a = 0x10000L after loop exit */
}
e->a <<= 1;
}
/* Fetch values from our compact representation of Table D.2:
* Qe values and probability estimation state machine
*/
sv = *st;
qe = jpeg_aritab[sv & 0x7F]; /* => Qe_Value */
nl = qe & 0xFF; qe >>= 8; /* Next_Index_LPS + Switch_MPS */
nm = qe & 0xFF; qe >>= 8; /* Next_Index_MPS */
/* Decode & estimation procedures per sections D.2.4 & D.2.5 */
temp = e->a - qe;
e->a = temp;
temp <<= e->ct;
if (e->c >= temp) {
e->c -= temp;
/* Conditional LPS (less probable symbol) exchange */
if (e->a < qe) {
e->a = qe;
*st = (sv & 0x80) ^ nm; /* Estimate_after_MPS */
} else {
e->a = qe;
*st = (sv & 0x80) ^ nl; /* Estimate_after_LPS */
sv ^= 0x80; /* Exchange LPS/MPS */
}
} else if (e->a < 0x8000L) {
/* Conditional MPS (more probable symbol) exchange */
if (e->a < qe) {
*st = (sv & 0x80) ^ nl; /* Estimate_after_LPS */
sv ^= 0x80; /* Exchange LPS/MPS */
} else {
*st = (sv & 0x80) ^ nm; /* Estimate_after_MPS */
}
}
return sv >> 7;
}
/*
* Check for a restart marker & resynchronize decoder.
*/
LOCAL(void)
process_restart (j_decompress_ptr cinfo)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
int ci;
jpeg_component_info * compptr;
/* Advance past the RSTn marker */
if (! (*cinfo->marker->read_restart_marker) (cinfo))
ERREXIT(cinfo, JERR_CANT_SUSPEND);
/* Re-initialize statistics areas */
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
if (! cinfo->progressive_mode || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
MEMZERO(entropy->dc_stats[compptr->dc_tbl_no], DC_STAT_BINS);
/* Reset DC predictions to 0 */
entropy->last_dc_val[ci] = 0;
entropy->dc_context[ci] = 0;
}
if (! cinfo->progressive_mode || cinfo->Ss) {
MEMZERO(entropy->ac_stats[compptr->ac_tbl_no], AC_STAT_BINS);
}
}
/* Reset arithmetic decoding variables */
entropy->c = 0;
entropy->a = 0;
entropy->ct = -16; /* force reading 2 initial bytes to fill C */
/* Reset restart counter */
entropy->restarts_to_go = cinfo->restart_interval;
}
/*
* Arithmetic MCU decoding.
* Each of these routines decodes and returns one MCU's worth of
* arithmetic-compressed coefficients.
* The coefficients are reordered from zigzag order into natural array order,
* but are not dequantized.
*
* The i'th block of the MCU is stored into the block pointed to by
* MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
*/
/*
* MCU decoding for DC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int blkn, ci, tbl, sign;
int v, m;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
if (entropy->ct == -1) return TRUE; /* if error do nothing */
/* Outer loop handles each block in the MCU */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
tbl = cinfo->cur_comp_info[ci]->dc_tbl_no;
/* Sections F.2.4.1 & F.1.4.4.1: Decoding of DC coefficients */
/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
/* Figure F.19: Decode_DC_DIFF */
if (arith_decode(cinfo, st) == 0)
entropy->dc_context[ci] = 0;
else {
/* Figure F.21: Decoding nonzero value v */
/* Figure F.22: Decoding the sign of v */
sign = arith_decode(cinfo, st + 1);
st += 2; st += sign;
/* Figure F.23: Decoding the magnitude category of v */
if ((m = arith_decode(cinfo, st)) != 0) {
st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
while (arith_decode(cinfo, st)) {
if ((m <<= 1) == 0x8000) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* magnitude overflow */
return TRUE;
}
st += 1;
}
}
/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
if (m < (int) ((1L << cinfo->arith_dc_L[tbl]) >> 1))
entropy->dc_context[ci] = 0; /* zero diff category */
else if (m > (int) ((1L << cinfo->arith_dc_U[tbl]) >> 1))
entropy->dc_context[ci] = 12 + (sign * 4); /* large diff category */
else
entropy->dc_context[ci] = 4 + (sign * 4); /* small diff category */
v = m;
/* Figure F.24: Decoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
if (arith_decode(cinfo, st)) v |= m;
v += 1; if (sign) v = -v;
entropy->last_dc_val[ci] += v;
}
/* Scale and output the DC coefficient (assumes jpeg_natural_order[0]=0) */
(*block)[0] = (JCOEF) (entropy->last_dc_val[ci] << cinfo->Al);
}
return TRUE;
}
/*
* MCU decoding for AC initial scan (either spectral selection,
* or first pass of successive approximation).
*/
METHODDEF(boolean)
decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
unsigned char *st;
int tbl, sign, k;
int v, m;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
if (entropy->ct == -1) return TRUE; /* if error do nothing */
/* There is always only one block per MCU */
block = MCU_data[0];
tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
/* Sections F.2.4.2 & F.1.4.4.2: Decoding of AC coefficients */
/* Figure F.20: Decode_AC_coefficients */
for (k = cinfo->Ss; k <= cinfo->Se; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
if (arith_decode(cinfo, st)) break; /* EOB flag */
while (arith_decode(cinfo, st + 1) == 0) {
st += 3; k++;
if (k > cinfo->Se) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* spectral overflow */
return TRUE;
}
}
/* Figure F.21: Decoding nonzero value v */
/* Figure F.22: Decoding the sign of v */
sign = arith_decode(cinfo, entropy->fixed_bin);
st += 2;
/* Figure F.23: Decoding the magnitude category of v */
if ((m = arith_decode(cinfo, st)) != 0) {
if (arith_decode(cinfo, st)) {
m <<= 1;
st = entropy->ac_stats[tbl] +
(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
while (arith_decode(cinfo, st)) {
if ((m <<= 1) == 0x8000) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* magnitude overflow */
return TRUE;
}
st += 1;
}
}
}
v = m;
/* Figure F.24: Decoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
if (arith_decode(cinfo, st)) v |= m;
v += 1; if (sign) v = -v;
/* Scale and output coefficient in natural (dezigzagged) order */
(*block)[jpeg_natural_order[k]] = (JCOEF) (v << cinfo->Al);
}
return TRUE;
}
/*
* MCU decoding for DC successive approximation refinement scan.
*/
METHODDEF(boolean)
decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
unsigned char *st;
int p1, blkn;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
st = entropy->fixed_bin; /* use fixed probability estimation */
p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
/* Outer loop handles each block in the MCU */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
/* Encoded data is simply the next bit of the two's-complement DC value */
if (arith_decode(cinfo, st))
MCU_data[blkn][0][0] |= p1;
}
return TRUE;
}
/*
* MCU decoding for AC successive approximation refinement scan.
*/
METHODDEF(boolean)
decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
JBLOCKROW block;
JCOEFPTR thiscoef;
unsigned char *st;
int tbl, k, kex;
int p1, m1;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
if (entropy->ct == -1) return TRUE; /* if error do nothing */
/* There is always only one block per MCU */
block = MCU_data[0];
tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */
/* Establish EOBx (previous stage end-of-block) index */
for (kex = cinfo->Se; kex > 0; kex--)
if ((*block)[jpeg_natural_order[kex]]) break;
for (k = cinfo->Ss; k <= cinfo->Se; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
if (k > kex)
if (arith_decode(cinfo, st)) break; /* EOB flag */
for (;;) {
thiscoef = *block + jpeg_natural_order[k];
if (*thiscoef) { /* previously nonzero coef */
if (arith_decode(cinfo, st + 2)) {
if (*thiscoef < 0)
*thiscoef += m1;
else
*thiscoef += p1;
}
break;
}
if (arith_decode(cinfo, st + 1)) { /* newly nonzero coef */
if (arith_decode(cinfo, entropy->fixed_bin))
*thiscoef = m1;
else
*thiscoef = p1;
break;
}
st += 3; k++;
if (k > cinfo->Se) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* spectral overflow */
return TRUE;
}
}
}
return TRUE;
}
/*
* Decode one MCU's worth of arithmetic-compressed coefficients.
*/
METHODDEF(boolean)
decode_mcu (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
jpeg_component_info * compptr;
JBLOCKROW block;
unsigned char *st;
int blkn, ci, tbl, sign, k;
int v, m;
/* Process restart marker if needed */
if (cinfo->restart_interval) {
if (entropy->restarts_to_go == 0)
process_restart(cinfo);
entropy->restarts_to_go--;
}
if (entropy->ct == -1) return TRUE; /* if error do nothing */
/* Outer loop handles each block in the MCU */
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
compptr = cinfo->cur_comp_info[ci];
/* Sections F.2.4.1 & F.1.4.4.1: Decoding of DC coefficients */
tbl = compptr->dc_tbl_no;
/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
/* Figure F.19: Decode_DC_DIFF */
if (arith_decode(cinfo, st) == 0)
entropy->dc_context[ci] = 0;
else {
/* Figure F.21: Decoding nonzero value v */
/* Figure F.22: Decoding the sign of v */
sign = arith_decode(cinfo, st + 1);
st += 2; st += sign;
/* Figure F.23: Decoding the magnitude category of v */
if ((m = arith_decode(cinfo, st)) != 0) {
st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
while (arith_decode(cinfo, st)) {
if ((m <<= 1) == 0x8000) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* magnitude overflow */
return TRUE;
}
st += 1;
}
}
/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
if (m < (int) ((1L << cinfo->arith_dc_L[tbl]) >> 1))
entropy->dc_context[ci] = 0; /* zero diff category */
else if (m > (int) ((1L << cinfo->arith_dc_U[tbl]) >> 1))
entropy->dc_context[ci] = 12 + (sign * 4); /* large diff category */
else
entropy->dc_context[ci] = 4 + (sign * 4); /* small diff category */
v = m;
/* Figure F.24: Decoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
if (arith_decode(cinfo, st)) v |= m;
v += 1; if (sign) v = -v;
entropy->last_dc_val[ci] += v;
}
(*block)[0] = (JCOEF) entropy->last_dc_val[ci];
/* Sections F.2.4.2 & F.1.4.4.2: Decoding of AC coefficients */
tbl = compptr->ac_tbl_no;
/* Figure F.20: Decode_AC_coefficients */
for (k = 1; k <= DCTSIZE2 - 1; k++) {
st = entropy->ac_stats[tbl] + 3 * (k - 1);
if (arith_decode(cinfo, st)) break; /* EOB flag */
while (arith_decode(cinfo, st + 1) == 0) {
st += 3; k++;
if (k > DCTSIZE2 - 1) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* spectral overflow */
return TRUE;
}
}
/* Figure F.21: Decoding nonzero value v */
/* Figure F.22: Decoding the sign of v */
sign = arith_decode(cinfo, entropy->fixed_bin);
st += 2;
/* Figure F.23: Decoding the magnitude category of v */
if ((m = arith_decode(cinfo, st)) != 0) {
if (arith_decode(cinfo, st)) {
m <<= 1;
st = entropy->ac_stats[tbl] +
(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
while (arith_decode(cinfo, st)) {
if ((m <<= 1) == 0x8000) {
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
entropy->ct = -1; /* magnitude overflow */
return TRUE;
}
st += 1;
}
}
}
v = m;
/* Figure F.24: Decoding the magnitude bit pattern of v */
st += 14;
while (m >>= 1)
if (arith_decode(cinfo, st)) v |= m;
v += 1; if (sign) v = -v;
(*block)[jpeg_natural_order[k]] = (JCOEF) v;
}
}
return TRUE;
}
/*
* Initialize for an arithmetic-compressed scan.
*/
METHODDEF(void)
start_pass (j_decompress_ptr cinfo)
{
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
int ci, tbl;
jpeg_component_info * compptr;
if (cinfo->progressive_mode) {
/* Validate progressive scan parameters */
if (cinfo->Ss == 0) {
if (cinfo->Se != 0)
goto bad;
} else {
/* need not check Ss/Se < 0 since they came from unsigned bytes */
if (cinfo->Se < cinfo->Ss || cinfo->Se > DCTSIZE2 - 1)
goto bad;
/* AC scans may have only one component */
if (cinfo->comps_in_scan != 1)
goto bad;
}
if (cinfo->Ah != 0) {
/* Successive approximation refinement scan: must have Al = Ah-1. */
if (cinfo->Ah-1 != cinfo->Al)
goto bad;
}
if (cinfo->Al > 13) { /* need not check for < 0 */
bad:
ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
}
/* Update progression status, and verify that scan order is legal.
* Note that inter-scan inconsistencies are treated as warnings
* not fatal errors ... not clear if this is right way to behave.
*/
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
int coefi, cindex = cinfo->cur_comp_info[ci]->component_index;
int *coef_bit_ptr = & cinfo->coef_bits[cindex][0];
if (cinfo->Ss && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
if (cinfo->Ah != expected)
WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
coef_bit_ptr[coefi] = cinfo->Al;
}
}
/* Select MCU decoding routine */
if (cinfo->Ah == 0) {
if (cinfo->Ss == 0)
entropy->pub.decode_mcu = decode_mcu_DC_first;
else
entropy->pub.decode_mcu = decode_mcu_AC_first;
} else {
if (cinfo->Ss == 0)
entropy->pub.decode_mcu = decode_mcu_DC_refine;
else
entropy->pub.decode_mcu = decode_mcu_AC_refine;
}
} else {
/* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.
* This ought to be an error condition, but we make it a warning.
*/
if (cinfo->Ss != 0 || cinfo->Ah != 0 || cinfo->Al != 0 ||
(cinfo->Se < DCTSIZE2 && cinfo->Se != DCTSIZE2 - 1))
WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);
/* Select MCU decoding routine */
entropy->pub.decode_mcu = decode_mcu;
}
/* Allocate & initialize requested statistics areas */
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
if (! cinfo->progressive_mode || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
tbl = compptr->dc_tbl_no;
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
if (entropy->dc_stats[tbl] == NULL)
entropy->dc_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, DC_STAT_BINS);
MEMZERO(entropy->dc_stats[tbl], DC_STAT_BINS);
/* Initialize DC predictions to 0 */
entropy->last_dc_val[ci] = 0;
entropy->dc_context[ci] = 0;
}
if (! cinfo->progressive_mode || cinfo->Ss) {
tbl = compptr->ac_tbl_no;
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
if (entropy->ac_stats[tbl] == NULL)
entropy->ac_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
((j_common_ptr) cinfo, JPOOL_IMAGE, AC_STAT_BINS);
MEMZERO(entropy->ac_stats[tbl], AC_STAT_BINS);
}
}
/* Initialize arithmetic decoding variables */
entropy->c = 0;
entropy->a = 0;
entropy->ct = -16; /* force reading 2 initial bytes to fill C */
/* Initialize restart counter */
entropy->restarts_to_go = cinfo->restart_interval;
}
/*
* Module initialization routine for arithmetic entropy decoding.
*/
GLOBAL(void)
jinit_arith_decoder (j_decompress_ptr cinfo)
{
arith_entropy_ptr entropy;
int i;
entropy = (arith_entropy_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(arith_entropy_decoder));
cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;
entropy->pub.start_pass = start_pass;
/* Mark tables unallocated */
for (i = 0; i < NUM_ARITH_TBLS; i++) {
entropy->dc_stats[i] = NULL;
entropy->ac_stats[i] = NULL;
}
/* Initialize index for fixed probability estimation */
entropy->fixed_bin[0] = 113;
if (cinfo->progressive_mode) {
/* Create progression status table */
int *coef_bit_ptr, ci;
cinfo->coef_bits = (int (*)[DCTSIZE2])
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
cinfo->num_components*DCTSIZE2*SIZEOF(int));
coef_bit_ptr = & cinfo->coef_bits[0][0];
for (ci = 0; ci < cinfo->num_components; ci++)
for (i = 0; i < DCTSIZE2; i++)
*coef_bit_ptr++ = -1;
}
}

4
jdmaster.c
View File

@@ -405,7 +405,11 @@ master_selection (j_decompress_ptr cinfo)
jinit_inverse_dct(cinfo);
/* Entropy decoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
#ifdef D_ARITH_CODING_SUPPORTED
jinit_arith_decoder(cinfo);
#else
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
#endif
} else {
if (cinfo->progressive_mode) {
#ifdef D_PROGRESSIVE_SUPPORTED

4
jdtrans.c
View File

@@ -101,7 +101,11 @@ transdecode_master_selection (j_decompress_ptr cinfo)
/* Entropy decoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
#ifdef D_ARITH_CODING_SUPPORTED
jinit_arith_decoder(cinfo);
#else
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
#endif
} else {
if (cinfo->progressive_mode) {
#ifdef D_PROGRESSIVE_SUPPORTED

2
jerror.h
View File

@@ -95,6 +95,7 @@ JMESSAGE(JERR_MISSING_DATA, "Scan script does not transmit all data")
JMESSAGE(JERR_MODE_CHANGE, "Invalid color quantization mode change")
JMESSAGE(JERR_NOTIMPL, "Not implemented yet")
JMESSAGE(JERR_NOT_COMPILED, "Requested feature was omitted at compile time")
JMESSAGE(JERR_NO_ARITH_TABLE, "Arithmetic table 0x%02x was not defined")
JMESSAGE(JERR_NO_BACKING_STORE, "Backing store not supported")
JMESSAGE(JERR_NO_HUFF_TABLE, "Huffman table 0x%02x was not defined")
JMESSAGE(JERR_NO_IMAGE, "JPEG datastream contains no image")
@@ -172,6 +173,7 @@ JMESSAGE(JTRC_UNKNOWN_IDS,
JMESSAGE(JTRC_XMS_CLOSE, "Freed XMS handle %u")
JMESSAGE(JTRC_XMS_OPEN, "Obtained XMS handle %u")
JMESSAGE(JWRN_ADOBE_XFORM, "Unknown Adobe color transform code %d")
JMESSAGE(JWRN_ARITH_BAD_CODE, "Corrupt JPEG data: bad arithmetic code")
JMESSAGE(JWRN_BOGUS_PROGRESSION,
"Inconsistent progression sequence for component %d coefficient %d")
JMESSAGE(JWRN_EXTRANEOUS_DATA,

6
jmorecfg.h
View File

@@ -257,8 +257,6 @@ typedef int boolean;
* (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. */
/* Capability options common to encoder and decoder: */
#define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */
@@ -267,7 +265,7 @@ typedef int boolean;
/* Encoder capability options: */
#undef C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
#define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
@@ -283,7 +281,7 @@ typedef int boolean;
/* Decoder capability options: */
#undef D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
#define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
#define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */

9
jpegint.h
View File

@@ -2,6 +2,7 @@
* jpegint.h
*
* Copyright (C) 1991-1997, Thomas G. Lane.
* Modified 1997-2009 by Guido Vollbeding.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
@@ -304,6 +305,7 @@ struct jpeg_color_quantizer {
#define jinit_forward_dct jIFDCT
#define jinit_huff_encoder jIHEncoder
#define jinit_phuff_encoder jIPHEncoder
#define jinit_arith_encoder jIAEncoder
#define jinit_marker_writer jIMWriter
#define jinit_master_decompress jIDMaster
#define jinit_d_main_controller jIDMainC
@@ -313,6 +315,7 @@ struct jpeg_color_quantizer {
#define jinit_marker_reader jIMReader
#define jinit_huff_decoder jIHDecoder
#define jinit_phuff_decoder jIPHDecoder
#define jinit_arith_decoder jIADecoder
#define jinit_inverse_dct jIIDCT
#define jinit_upsampler jIUpsampler
#define jinit_color_deconverter jIDColor
@@ -327,6 +330,7 @@ struct jpeg_color_quantizer {
#define jzero_far jZeroFar
#define jpeg_zigzag_order jZIGTable
#define jpeg_natural_order jZAGTable
#define jpeg_aritab jAriTab
#endif /* NEED_SHORT_EXTERNAL_NAMES */
@@ -345,6 +349,7 @@ EXTERN(void) jinit_downsampler JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_forward_dct JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_huff_encoder JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_phuff_encoder JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_arith_encoder JPP((j_compress_ptr cinfo));
EXTERN(void) jinit_marker_writer JPP((j_compress_ptr cinfo));
/* Decompression module initialization routines */
EXTERN(void) jinit_master_decompress JPP((j_decompress_ptr cinfo));
@@ -358,6 +363,7 @@ EXTERN(void) jinit_input_controller JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_marker_reader JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_huff_decoder JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_phuff_decoder JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_arith_decoder JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_inverse_dct JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_upsampler JPP((j_decompress_ptr cinfo));
EXTERN(void) jinit_color_deconverter JPP((j_decompress_ptr cinfo));
@@ -382,6 +388,9 @@ extern const int jpeg_zigzag_order[]; /* natural coef order to zigzag order */
#endif
extern const int jpeg_natural_order[]; /* zigzag coef order to natural order */
/* Arithmetic coding probability estimation tables in jaricom.c */
extern const INT32 jpeg_aritab[];
/* Suppress undefined-structure complaints if necessary. */
#ifdef INCOMPLETE_TYPES_BROKEN

5
jpegtran.1
View File

@@ -60,6 +60,9 @@ Create progressive JPEG file.
Emit a JPEG restart marker every N MCU rows, or every N MCU blocks if "B" is
attached to the number.
.TP
.B \-arithmetic
Use arithmetic coding.
.TP
.BI \-scans " file"
Use the scan script given in the specified text file.
.PP
@@ -249,8 +252,6 @@ Communications of the ACM, April 1991 (vol. 34, no. 4), pp. 30-44.
.SH AUTHOR
Independent JPEG Group
.SH BUGS
Arithmetic coding is not supported for legal reasons.
.PP
The transform options can't transform odd-size images perfectly. Use
.B \-trim
or

6
libjpeg.txt
View File

@@ -93,7 +93,6 @@ JPEG processes are supported. (Our subset includes all features now in common
use.) Unsupported ISO options include:
* Hierarchical storage
* Lossless JPEG
* Arithmetic entropy coding (unsupported for legal reasons)
* DNL marker
* Nonintegral subsampling ratios
We support both 8- and 12-bit data precision, but this is a compile-time
@@ -1023,11 +1022,6 @@ JDIMENSION jpeg_width Actual dimensions of output image.
JDIMENSION jpeg_height
There are some additional cinfo fields which are not documented here
because you currently can't change them; for example, you can't set
arith_code TRUE because arithmetic coding is unsupported.
Per-component parameters are stored in the struct cinfo.comp_info[i] for
component number i. Note that components here refer to components of the
JPEG color space, *not* the source image color space. A suitably large

3
structure.txt
View File

@@ -60,9 +60,6 @@ we treat 8-bit vs. 12-bit data precision as a compile-time switch, not a
run-time option, because most machines can store 8-bit pixels much more
compactly than 12-bit.
For legal reasons, JPEG arithmetic coding is not currently supported, but
extending the library to include it would be straightforward.
By itself, the library handles only interchange JPEG datastreams --- in
particular the widely used JFIF file format. The library can be used by
surrounding code to process interchange or abbreviated JPEG datastreams that

BIN
testimgari.jpg Normal file
View File

Binary file not shown.
Side by Side

After

Width:  |  Height:  |  Size: 5.0 KiB

4
testimgari.ppm Normal file
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File diff suppressed because one or more lines are too long

6
usage.txt
View File

@@ -201,6 +201,11 @@ factor will visibly blur the image, however.
Switches for wizards:
-arithmetic Use arithmetic coding. CAUTION: arithmetic coded JPEG
is not yet widely implemented, so many decoders will
be unable to view an arithmetic coded JPEG file at
all.
-baseline Force baseline-compatible quantization tables to be
generated. This clamps quantization values to 8 bits
even at low quality settings. (This switch is poorly
@@ -444,6 +449,7 @@ jpegtran accepts a subset of the switches recognized by cjpeg:
-progressive Create progressive JPEG file.
-restart N Emit a JPEG restart marker every N MCU rows, or every
N MCU blocks if "B" is attached to the number.
-arithmetic Use arithmetic coding.
-scans file Use the scan script given in the specified text file.
See the previous discussion of cjpeg for more details about these switches.
If you specify none of these switches, you get a plain baseline-JPEG output