source: trunk/libjpeg/change.log @ 426

Last change on this file since 426 was 283, checked in by rbri, 12 years ago

JPEG plugin: libjpeg updated to version 7

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Line 
1CHANGE LOG for Independent JPEG Group's JPEG software
2
3
4Version 7  27-Jun-2009
5----------------------
6
7New scaled DCTs implemented.
8djpeg now supports scalings N/8 with all N from 1 to 16.
9cjpeg now supports scalings 8/N with all N from 1 to 16.
10Scaled DCTs with size larger than 8 are now also used for resolving the
11common 2x2 chroma subsampling case without additional spatial resampling.
12Separate spatial resampling for those kind of files is now only necessary
13for N>8 scaling cases.
14Furthermore, separate scaled DCT functions are provided for direct resolving
15of the common asymmetric subsampling cases (2x1 and 1x2) without additional
16spatial resampling.
17
18cjpeg -quality option has been extended for support of separate quality
19settings for luminance and chrominance (or in general, for every provided
20quantization table slot).
21New API function jpeg_default_qtables() and q_scale_factor array in library.
22
23Added -nosmooth option to cjpeg, complementary to djpeg.
24New variable "do_fancy_downsampling" in library, complement to fancy
25upsampling.  Fancy upsampling now uses direct DCT scaling with sizes
26larger than 8.  The old method is not reversible and has been removed.
27
28Support arithmetic entropy encoding and decoding.
29Added files jaricom.c, jcarith.c, jdarith.c.
30
31Straighten the file structure:
32Removed files jidctred.c, jcphuff.c, jchuff.h, jdphuff.c, jdhuff.h.
33
34jpegtran has a new "lossless" cropping feature.
35
36Implement -perfect option in jpegtran, new API function
37jtransform_perfect_transform() in transupp. (DP 204_perfect.dpatch)
38
39Better error messages for jpegtran fopen failure.
40(DP 203_jpegtran_errmsg.dpatch)
41
42Fix byte order issue with 16bit PPM/PGM files in rdppm.c/wrppm.c:
43according to Netpbm, the de facto standard implementation of the PNM formats,
44the most significant byte is first. (DP 203_rdppm.dpatch)
45
46Add -raw option to rdjpgcom not to mangle the output.
47(DP 205_rdjpgcom_raw.dpatch)
48
49Make rdjpgcom locale aware. (DP 201_rdjpgcom_locale.dpatch)
50
51Add extern "C" to jpeglib.h.
52This avoids the need to put extern "C" { ... } around #include "jpeglib.h"
53in your C++ application.  Defining the symbol DONT_USE_EXTERN_C in the
54configuration prevents this. (DP 202_jpeglib.h_c++.dpatch)
55
56
57Version 6b  27-Mar-1998
58-----------------------
59
60jpegtran has new features for lossless image transformations (rotation
61and flipping) as well as "lossless" reduction to grayscale.
62
63jpegtran now copies comments by default; it has a -copy switch to enable
64copying all APPn blocks as well, or to suppress comments.  (Formerly it
65always suppressed comments and APPn blocks.)  jpegtran now also preserves
66JFIF version and resolution information.
67
68New decompressor library feature: COM and APPn markers found in the input
69file can be saved in memory for later use by the application.  (Before,
70you had to code this up yourself with a custom marker processor.)
71
72There is an unused field "void * client_data" now in compress and decompress
73parameter structs; this may be useful in some applications.
74
75JFIF version number information is now saved by the decoder and accepted by
76the encoder.  jpegtran uses this to copy the source file's version number,
77to ensure "jpegtran -copy all" won't create bogus files that contain JFXX
78extensions but claim to be version 1.01.  Applications that generate their
79own JFXX extension markers also (finally) have a supported way to cause the
80encoder to emit JFIF version number 1.02.
81
82djpeg's trace mode reports JFIF 1.02 thumbnail images as such, rather
83than as unknown APP0 markers.
84
85In -verbose mode, djpeg and rdjpgcom will try to print the contents of
86APP12 markers as text.  Some digital cameras store useful text information
87in APP12 markers.
88
89Handling of truncated data streams is more robust: blocks beyond the one in
90which the error occurs will be output as uniform gray, or left unchanged
91if decoding a progressive JPEG.  The appearance no longer depends on the
92Huffman tables being used.
93
94Huffman tables are checked for validity much more carefully than before.
95
96To avoid the Unisys LZW patent, djpeg's GIF output capability has been
97changed to produce "uncompressed GIFs", and cjpeg's GIF input capability
98has been removed altogether.  We're not happy about it either, but there
99seems to be no good alternative.
100
101The configure script now supports building libjpeg as a shared library
102on many flavors of Unix (all the ones that GNU libtool knows how to
103build shared libraries for).  Use "./configure --enable-shared" to
104try this out.
105
106New jconfig file and makefiles for Microsoft Visual C++ and Developer Studio.
107Also, a jconfig file and a build script for Metrowerks CodeWarrior
108on Apple Macintosh.  makefile.dj has been updated for DJGPP v2, and there
109are miscellaneous other minor improvements in the makefiles.
110
111jmemmac.c now knows how to create temporary files following Mac System 7
112conventions.
113
114djpeg's -map switch is now able to read raw-format PPM files reliably.
115
116cjpeg -progressive -restart no longer generates any unnecessary DRI markers.
117
118Multiple calls to jpeg_simple_progression for a single JPEG object
119no longer leak memory.
120
121
122Version 6a  7-Feb-96
123--------------------
124
125Library initialization sequence modified to detect version mismatches
126and struct field packing mismatches between library and calling application.
127This change requires applications to be recompiled, but does not require
128any application source code change.
129
130All routine declarations changed to the style "GLOBAL(type) name ...",
131that is, GLOBAL, LOCAL, METHODDEF, EXTERN are now macros taking the
132routine's return type as an argument.  This makes it possible to add
133Microsoft-style linkage keywords to all the routines by changing just
134these macros.  Note that any application code that was using these macros
135will have to be changed.
136
137DCT coefficient quantization tables are now stored in normal array order
138rather than zigzag order.  Application code that calls jpeg_add_quant_table,
139or otherwise manipulates quantization tables directly, will need to be
140changed.  If you need to make such code work with either older or newer
141versions of the library, a test like "#if JPEG_LIB_VERSION >= 61" is
142recommended.
143
144djpeg's trace capability now dumps DQT tables in natural order, not zigzag
145order.  This allows the trace output to be made into a "-qtables" file
146more easily.
147
148New system-dependent memory manager module for use on Apple Macintosh.
149
150Fix bug in cjpeg's -smooth option: last one or two scanlines would be
151duplicates of the prior line unless the image height mod 16 was 1 or 2.
152
153Repair minor problems in VMS, BCC, MC6 makefiles.
154
155New configure script based on latest GNU Autoconf.
156
157Correct the list of include files needed by MetroWerks C for ccommand().
158
159Numerous small documentation updates.
160
161
162Version 6  2-Aug-95
163-------------------
164
165Progressive JPEG support: library can read and write full progressive JPEG
166files.  A "buffered image" mode supports incremental decoding for on-the-fly
167display of progressive images.  Simply recompiling an existing IJG-v5-based
168decoder with v6 should allow it to read progressive files, though of course
169without any special progressive display.
170
171New "jpegtran" application performs lossless transcoding between different
172JPEG formats; primarily, it can be used to convert baseline to progressive
173JPEG and vice versa.  In support of jpegtran, the library now allows lossless
174reading and writing of JPEG files as DCT coefficient arrays.  This ability
175may be of use in other applications.
176
177Notes for programmers:
178* We changed jpeg_start_decompress() to be able to suspend; this makes all
179decoding modes available to suspending-input applications.  However,
180existing applications that use suspending input will need to be changed
181to check the return value from jpeg_start_decompress().  You don't need to
182do anything if you don't use a suspending data source.
183* We changed the interface to the virtual array routines: access_virt_array
184routines now take a count of the number of rows to access this time.  The
185last parameter to request_virt_array routines is now interpreted as the
186maximum number of rows that may be accessed at once, but not necessarily
187the height of every access.
188
189
190Version 5b  15-Mar-95
191---------------------
192
193Correct bugs with grayscale images having v_samp_factor > 1.
194
195jpeg_write_raw_data() now supports output suspension.
196
197Correct bugs in "configure" script for case of compiling in
198a directory other than the one containing the source files.
199
200Repair bug in jquant1.c: sometimes didn't use as many colors as it could.
201
202Borland C makefile and jconfig file work under either MS-DOS or OS/2.
203
204Miscellaneous improvements to documentation.
205
206
207Version 5a  7-Dec-94
208--------------------
209
210Changed color conversion roundoff behavior so that grayscale values are
211represented exactly.  (This causes test image files to change.)
212
213Make ordered dither use 16x16 instead of 4x4 pattern for a small quality
214improvement.
215
216New configure script based on latest GNU Autoconf.
217Fix configure script to handle CFLAGS correctly.
218Rename *.auto files to *.cfg, so that configure script still works if
219file names have been truncated for DOS.
220
221Fix bug in rdbmp.c: didn't allow for extra data between header and image.
222
223Modify rdppm.c/wrppm.c to handle 2-byte raw PPM/PGM formats for 12-bit data.
224
225Fix several bugs in rdrle.c.
226
227NEED_SHORT_EXTERNAL_NAMES option was broken.
228
229Revise jerror.h/jerror.c for more flexibility in message table.
230
231Repair oversight in jmemname.c NO_MKTEMP case: file could be there
232but unreadable.
233
234
235Version 5  24-Sep-94
236--------------------
237
238Version 5 represents a nearly complete redesign and rewrite of the IJG
239software.  Major user-visible changes include:
240  * Automatic configuration simplifies installation for most Unix systems.
241  * A range of speed vs. image quality tradeoffs are supported.
242    This includes resizing of an image during decompression: scaling down
243    by a factor of 1/2, 1/4, or 1/8 is handled very efficiently.
244  * New programs rdjpgcom and wrjpgcom allow insertion and extraction
245    of text comments in a JPEG file.
246
247The application programmer's interface to the library has changed completely.
248Notable improvements include:
249  * We have eliminated the use of callback routines for handling the
250    uncompressed image data.  The application now sees the library as a
251    set of routines that it calls to read or write image data on a
252    scanline-by-scanline basis.
253  * The application image data is represented in a conventional interleaved-
254    pixel format, rather than as a separate array for each color channel.
255    This can save a copying step in many programs.
256  * The handling of compressed data has been cleaned up: the application can
257    supply routines to source or sink the compressed data.  It is possible to
258    suspend processing on source/sink buffer overrun, although this is not
259    supported in all operating modes.
260  * All static state has been eliminated from the library, so that multiple
261    instances of compression or decompression can be active concurrently.
262  * JPEG abbreviated datastream formats are supported, ie, quantization and
263    Huffman tables can be stored separately from the image data.
264  * And not only that, but the documentation of the library has improved
265    considerably!
266
267
268The last widely used release before the version 5 rewrite was version 4A of
26918-Feb-93.  Change logs before that point have been discarded, since they
270are not of much interest after the rewrite.
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