source: trunk/libjpeg/change.log @ 15

Last change on this file since 15 was 15, checked in by Eugene Romanenko, 15 years ago

needed libs update

File size: 9.3 KB
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1CHANGE LOG for Independent JPEG Group's JPEG software
2
3
4Version 6b  27-Mar-1998
5-----------------------
6
7jpegtran has new features for lossless image transformations (rotation
8and flipping) as well as "lossless" reduction to grayscale.
9
10jpegtran now copies comments by default; it has a -copy switch to enable
11copying all APPn blocks as well, or to suppress comments.  (Formerly it
12always suppressed comments and APPn blocks.)  jpegtran now also preserves
13JFIF version and resolution information.
14
15New decompressor library feature: COM and APPn markers found in the input
16file can be saved in memory for later use by the application.  (Before,
17you had to code this up yourself with a custom marker processor.)
18
19There is an unused field "void * client_data" now in compress and decompress
20parameter structs; this may be useful in some applications.
21
22JFIF version number information is now saved by the decoder and accepted by
23the encoder.  jpegtran uses this to copy the source file's version number,
24to ensure "jpegtran -copy all" won't create bogus files that contain JFXX
25extensions but claim to be version 1.01.  Applications that generate their
26own JFXX extension markers also (finally) have a supported way to cause the
27encoder to emit JFIF version number 1.02.
28
29djpeg's trace mode reports JFIF 1.02 thumbnail images as such, rather
30than as unknown APP0 markers.
31
32In -verbose mode, djpeg and rdjpgcom will try to print the contents of
33APP12 markers as text.  Some digital cameras store useful text information
34in APP12 markers.
35
36Handling of truncated data streams is more robust: blocks beyond the one in
37which the error occurs will be output as uniform gray, or left unchanged
38if decoding a progressive JPEG.  The appearance no longer depends on the
39Huffman tables being used.
40
41Huffman tables are checked for validity much more carefully than before.
42
43To avoid the Unisys LZW patent, djpeg's GIF output capability has been
44changed to produce "uncompressed GIFs", and cjpeg's GIF input capability
45has been removed altogether.  We're not happy about it either, but there
46seems to be no good alternative.
47
48The configure script now supports building libjpeg as a shared library
49on many flavors of Unix (all the ones that GNU libtool knows how to
50build shared libraries for).  Use "./configure --enable-shared" to
51try this out.
52
53New jconfig file and makefiles for Microsoft Visual C++ and Developer Studio.
54Also, a jconfig file and a build script for Metrowerks CodeWarrior
55on Apple Macintosh.  makefile.dj has been updated for DJGPP v2, and there
56are miscellaneous other minor improvements in the makefiles.
57
58jmemmac.c now knows how to create temporary files following Mac System 7
59conventions.
60
61djpeg's -map switch is now able to read raw-format PPM files reliably.
62
63cjpeg -progressive -restart no longer generates any unnecessary DRI markers.
64
65Multiple calls to jpeg_simple_progression for a single JPEG object
66no longer leak memory.
67
68
69Version 6a  7-Feb-96
70--------------------
71
72Library initialization sequence modified to detect version mismatches
73and struct field packing mismatches between library and calling application.
74This change requires applications to be recompiled, but does not require
75any application source code change.
76
77All routine declarations changed to the style "GLOBAL(type) name ...",
78that is, GLOBAL, LOCAL, METHODDEF, EXTERN are now macros taking the
79routine's return type as an argument.  This makes it possible to add
80Microsoft-style linkage keywords to all the routines by changing just
81these macros.  Note that any application code that was using these macros
82will have to be changed.
83
84DCT coefficient quantization tables are now stored in normal array order
85rather than zigzag order.  Application code that calls jpeg_add_quant_table,
86or otherwise manipulates quantization tables directly, will need to be
87changed.  If you need to make such code work with either older or newer
88versions of the library, a test like "#if JPEG_LIB_VERSION >= 61" is
89recommended.
90
91djpeg's trace capability now dumps DQT tables in natural order, not zigzag
92order.  This allows the trace output to be made into a "-qtables" file
93more easily.
94
95New system-dependent memory manager module for use on Apple Macintosh.
96
97Fix bug in cjpeg's -smooth option: last one or two scanlines would be
98duplicates of the prior line unless the image height mod 16 was 1 or 2.
99
100Repair minor problems in VMS, BCC, MC6 makefiles.
101
102New configure script based on latest GNU Autoconf.
103
104Correct the list of include files needed by MetroWerks C for ccommand().
105
106Numerous small documentation updates.
107
108
109Version 6  2-Aug-95
110-------------------
111
112Progressive JPEG support: library can read and write full progressive JPEG
113files.  A "buffered image" mode supports incremental decoding for on-the-fly
114display of progressive images.  Simply recompiling an existing IJG-v5-based
115decoder with v6 should allow it to read progressive files, though of course
116without any special progressive display.
117
118New "jpegtran" application performs lossless transcoding between different
119JPEG formats; primarily, it can be used to convert baseline to progressive
120JPEG and vice versa.  In support of jpegtran, the library now allows lossless
121reading and writing of JPEG files as DCT coefficient arrays.  This ability
122may be of use in other applications.
123
124Notes for programmers:
125* We changed jpeg_start_decompress() to be able to suspend; this makes all
126decoding modes available to suspending-input applications.  However,
127existing applications that use suspending input will need to be changed
128to check the return value from jpeg_start_decompress().  You don't need to
129do anything if you don't use a suspending data source.
130* We changed the interface to the virtual array routines: access_virt_array
131routines now take a count of the number of rows to access this time.  The
132last parameter to request_virt_array routines is now interpreted as the
133maximum number of rows that may be accessed at once, but not necessarily
134the height of every access.
135
136
137Version 5b  15-Mar-95
138---------------------
139
140Correct bugs with grayscale images having v_samp_factor > 1.
141
142jpeg_write_raw_data() now supports output suspension.
143
144Correct bugs in "configure" script for case of compiling in
145a directory other than the one containing the source files.
146
147Repair bug in jquant1.c: sometimes didn't use as many colors as it could.
148
149Borland C makefile and jconfig file work under either MS-DOS or OS/2.
150
151Miscellaneous improvements to documentation.
152
153
154Version 5a  7-Dec-94
155--------------------
156
157Changed color conversion roundoff behavior so that grayscale values are
158represented exactly.  (This causes test image files to change.)
159
160Make ordered dither use 16x16 instead of 4x4 pattern for a small quality
161improvement.
162
163New configure script based on latest GNU Autoconf.
164Fix configure script to handle CFLAGS correctly.
165Rename *.auto files to *.cfg, so that configure script still works if
166file names have been truncated for DOS.
167
168Fix bug in rdbmp.c: didn't allow for extra data between header and image.
169
170Modify rdppm.c/wrppm.c to handle 2-byte raw PPM/PGM formats for 12-bit data.
171
172Fix several bugs in rdrle.c.
173
174NEED_SHORT_EXTERNAL_NAMES option was broken.
175
176Revise jerror.h/jerror.c for more flexibility in message table.
177
178Repair oversight in jmemname.c NO_MKTEMP case: file could be there
179but unreadable.
180
181
182Version 5  24-Sep-94
183--------------------
184
185Version 5 represents a nearly complete redesign and rewrite of the IJG
186software.  Major user-visible changes include:
187  * Automatic configuration simplifies installation for most Unix systems.
188  * A range of speed vs. image quality tradeoffs are supported.
189    This includes resizing of an image during decompression: scaling down
190    by a factor of 1/2, 1/4, or 1/8 is handled very efficiently.
191  * New programs rdjpgcom and wrjpgcom allow insertion and extraction
192    of text comments in a JPEG file.
193
194The application programmer's interface to the library has changed completely.
195Notable improvements include:
196  * We have eliminated the use of callback routines for handling the
197    uncompressed image data.  The application now sees the library as a
198    set of routines that it calls to read or write image data on a
199    scanline-by-scanline basis.
200  * The application image data is represented in a conventional interleaved-
201    pixel format, rather than as a separate array for each color channel.
202    This can save a copying step in many programs.
203  * The handling of compressed data has been cleaned up: the application can
204    supply routines to source or sink the compressed data.  It is possible to
205    suspend processing on source/sink buffer overrun, although this is not
206    supported in all operating modes.
207  * All static state has been eliminated from the library, so that multiple
208    instances of compression or decompression can be active concurrently.
209  * JPEG abbreviated datastream formats are supported, ie, quantization and
210    Huffman tables can be stored separately from the image data.
211  * And not only that, but the documentation of the library has improved
212    considerably!
213
214
215The last widely used release before the version 5 rewrite was version 4A of
21618-Feb-93.  Change logs before that point have been discarded, since they
217are not of much interest after the rewrite.
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