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6e632af9
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2020-11-04T10:13:06
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Demote "fast" [I]DCT algorithms to legacy status
- Refer to the "slow" [I]DCT algorithms as "accurate" instead, since
they are not slow under libjpeg-turbo.
- Adjust documentation claims to reflect the fact that the "slow" and
"fast" algorithms produce about the same performance on AVX2-equipped
CPUs (because of the dual-lane nature of AVX2, it was not possible to
accelerate the "fast" algorithm beyond what was achievable with SSE2.)
Also adjust the claims to reflect the fact that the "fast" algorithm
tends to be ~5-15% faster than the "slow" algorithm on
non-AVX2-equipped CPUs, regardless of the use of the libjpeg-turbo
SIMD extensions.
- Indicate the legacy status of the "fast" and float algorithms in the
documentation and cjpeg/djpeg usage info.
- Remove obsolete paragraph in the djpeg man page that suggested that
the float algorithm could be faster than the "fast" algorithm on some
CPUs.
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9fc018fd
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2020-01-12T00:00:00
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The Independent JPEG Group's JPEG software v9d
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a46c111d
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2020-07-27T14:21:23
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Further jpeg_skip_scanlines() fixes
- Introduce a partial image decompression regression test script that
validates the correctness of jpeg_skip_scanlines() and
jpeg_crop_scanlines() for a variety of cropping regions and libjpeg
settings.
This regression test catches the following issues:
#182, fixed in 5bc43c7821df982f65aa1c738f67fbf7cba8bd69
#237, fixed in 6e95c08649794f5018608f37250026a45ead2db8
#244, fixed in 398c1e9acc9b4531edceb3d77da0de5744675052
#441, fully fixed in this commit
It does not catch the following issues:
#194, fixed in 773040f9d949d5f313caf7507abaf4bd5d7ffa12
#244 (additional segfault), fixed in
9120a247436e84c0b4eea828cb11e8f665fcde30
- Modify the libjpeg-turbo regression test suite (make test) so that it
checks for the issue reported in #441 (segfault in
jpeg_skip_scanlines() when used with 4:2:0 merged upsampling/color
conversion.)
- Fix issues in jpeg_skip_scanlines() that caused incorrect output with
h2v2 (4:2:0) merged upsampling/color conversion. The previous commit
fixed the segfault reported in #441, but that was a symptom of a
larger problem. Because merged 4:2:0 upsampling uses a "spare row"
buffer, it is necessary to allow the upsampler to run when skipping
rows (fancy 4:2:0 upsampling, which uses context rows, also requires
this.) Otherwise, if skipping starts at an odd-numbered row, the
output image will be incorrect.
- Throw an error if jpeg_skip_scanlines() is called with two-pass color
quantization enabled. With two-pass color quantization, the first
pass occurs within jpeg_start_decompress(), so subsequent calls to
jpeg_skip_scanlines() interfere with the multipass state and prevent
the second pass from occurring during subsequent calls to
jpeg_read_scanlines().
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a6289526
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2018-07-24T18:36:51
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Fix JPEG spec references per ISO/ITU-T suggestions
- When referring to specific clauses, annexes, tables, and figures, a
"timed reference" (a reference that includes the year) must be used in
order to avoid confusion.
- "CCITT" = "ITU-T"
- Replace ambiguous "JPEG spec" with the specific document number.
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19c791cd
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2018-03-08T10:55:20
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Improve code formatting consistency
With rare exceptions ...
- Always separate line continuation characters by one space from
preceding code.
- Always use two-space indentation. Never use tabs.
- Always use K&R-style conditional blocks.
- Always surround operators with spaces, except in raw assembly code.
- Always put a space after, but not before, a comma.
- Never put a space between type casts and variables/function calls.
- Never put a space between the function name and the argument list in
function declarations and prototypes.
- Always surround braces ('{' and '}') with spaces.
- Always surround statements (if, for, else, catch, while, do, switch)
with spaces.
- Always attach pointer symbols ('*' and '**') to the variable or
function name.
- Always precede pointer symbols ('*' and '**') by a space in type
casts.
- Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG
API libraries (using min() from tjutil.h is still necessary for
TJBench.)
- Where it makes sense (particularly in the TurboJPEG code), put a blank
line after variable declaration blocks.
- Always separate statements in one-liners by two spaces.
The purpose of this was to ease maintenance on my part and also to make
it easier for contributors to figure out how to format patch
submissions. This was admittedly confusing (even to me sometimes) when
we had 3 or 4 different style conventions in the same source tree. The
new convention is more consistent with the formatting of other OSS code
bases.
This commit corrects deviations from the chosen formatting style in the
libjpeg API code and reformats the TurboJPEG API code such that it
conforms to the same standard.
NOTES:
- Although it is no longer necessary for the function name in function
declarations to begin in Column 1 (this was historically necessary
because of the ansi2knr utility, which allowed libjpeg to be built
with non-ANSI compilers), we retain that formatting for the libjpeg
code because it improves readability when using libjpeg's function
attribute macros (GLOBAL(), etc.)
- This reformatting project was accomplished with the help of AStyle and
Uncrustify, although neither was completely up to the task, and thus
a great deal of manual tweaking was required. Note to developers of
code formatting utilities: the libjpeg-turbo code base is an
excellent test bed, because AFAICT, it breaks every single one of the
utilities that are currently available.
- The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been
formatted to match the SSE2 code (refer to
ff5685d5344273df321eb63a005eaae19d2496e3.) I hadn't intended to
bother with this, but the Loongson MMI implementation demonstrated
that there is still academic value to the MMX implementation, as an
algorithmic model for other 64-bit vector implementations. Thus, it
is desirable to improve its readability in the same manner as that of
the SSE2 implementation.
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8c40ac8a
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2017-11-16T18:46:01
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Add TurboJPEG C example and clean up Java example
Also rename example.c --> example.txt and add a disclaimer to that file
so people will stop trying to compile it.
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2ac4e9d9
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2017-06-26T21:58:32
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Merge branch 'master' into dev
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da2a27ef
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2017-03-18T16:15:14
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Honor max_memory_to_use/JPEGMEM/-maxmemory
This re-introduces a feature of the obsolete system-specific libjpeg
memory managers-- namely the ability to limit the amount of main memory
used by the library during decompression or multi-pass compression.
This is mainly beneficial for two reasons:
- Works around a 2 GB limit in libFuzzer
- Allows security-sensitive applications to set a memory limit for the
JPEG decoder so as to work around the progressive JPEG exploit
(LJT-01-004) described here:
http://www.libjpeg-turbo.org/pmwiki/uploads/About/TwoIssueswiththeJPEGStandard.pdf
This commit also removes obsolete documentation regarding the MS-DOS
memory manager (which itself was removed long ago) and changes the
documentation of the -maxmemory switch and JPEGMEM environment variable
to reflect the fact that backing stores are never used in libjpeg-turbo.
Inspired by:
https://github.com/caolanm/libjpeg-turbo/commit/066fee2e7d6834f24838bc1896aa38ca77209e3c
Closes #143
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44b2399a
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2017-01-19T15:18:57
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libjpeg API: Support reading/writing ICC profiles
This commit does the following:
-- Merges the two glueware functions (read_icc_profile() and
write_icc_profile()) from iccjpeg.c, which is contained in downstream
projects such as LCMS, Ghostscript, Mozilla, etc. These functions were
originally intended for inclusion in libjpeg, but Tom Lane left the IJG
before that could be accomplished. Since then, programs and libraries
that needed to embed/extract ICC profiles in JPEG files had to include
their own local copy of iccjpeg.c, which is suboptimal.
-- The new functions were prefixed with jpeg_ and split into separate
files for the compressor and decompressor, per the existing libjpeg
coding standards.
-- jpeg_write_icc_profile() was made slightly more fault-tolerant.
It will now trigger a libjpeg error if it is called before
jpeg_start_compress() or if it is passed NULL arguments.
-- jpeg_read_icc_profile() was made slightly more fault-tolerant.
It will now trigger a libjpeg error if it is called before
jpeg_read_header() or if it is passed NULL arguments. It will also
now trigger libjpeg warnings if the ICC profile data is corrupt.
-- The code comments have been wordsmithed.
-- Note that the one-line setup_read_icc_profile() function was not
included. Instead, libjpeg.txt now documents the need to call
jpeg_save_markers(cinfo, JPEG_APP0 + 2, 0xFFFF) prior to calling
jpeg_read_header(), if jpeg_read_icc_profile() is to be used.
-- Adds documentation for the new functions to libjpeg.txt.
-- Adds an -icc switch to cjpeg and jpegtran that allows those programs
to embed an ICC profile in the JPEG files they generate.
-- Adds an -icc switch to djpeg that allows that program to extract an
ICC profile from a JPEG file while decompressing.
-- Adds appropriate unit tests for all of the above.
-- Bumps the SO_AGE of the libjpeg API library to indicate the presence
of new API functions.
Note that the licensing information was obtained from:
https://github.com/mm2/Little-CMS/issues/37#issuecomment-66450180
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47b29e8c
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2017-01-19T15:36:58
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libjpeg.txt: Include partial decomp. in TOC
(oversight)
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3ab68cf5
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2016-02-19T18:32:10
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libjpeg API: Partial scanline decompression
This, in combination with the existing jpeg_skip_scanlines() function,
provides the ability to crop the image both horizontally and vertically
while decompressing (certain restrictions apply-- see libjpeg.txt.)
This also cleans up the documentation of the line skipping feature and
removes the "strip decompression" feature from djpeg, since the new
cropping feature is a superset of it.
Refer to #34 for discussion.
Closes #34
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bd49803f
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2016-02-19T08:53:33
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Use consistent/modern code formatting for pointers
The convention used by libjpeg:
type * variable;
is not very common anymore, because it looks too much like
multiplication. Some (particularly C++ programmers) prefer to tuck the
pointer symbol against the type:
type* variable;
to emphasize that a pointer to a type is effectively a new type.
However, this can also be confusing, since defining multiple variables
on the same line would not work properly:
type* variable1, variable2; /* Only variable1 is actually a
pointer. */
This commit reformats the entirety of the libjpeg-turbo code base so
that it uses the same code formatting convention for pointers that the
TurboJPEG API code uses:
type *variable1, *variable2;
This seems to be the most common convention among C programmers, and
it is the convention used by other codec libraries, such as libpng and
libtiff.
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54e6b8e8
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2016-02-18T15:16:17
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Include some comments/doc tweaks from jpeg-9+
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fc11193e
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2014-01-19T00:00:00
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The Independent JPEG Group's JPEG software v9a
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e7f88aec
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2013-01-13T00:00:00
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The Independent JPEG Group's JPEG software v9
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7e3acc0e
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2015-10-10T10:25:46
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Rename README, LICENSE, BUILDING text files
The IJG README file has been renamed to README.ijg, in order to avoid
confusion (many people were assuming that that was our project's README
file and weren't reading README-turbo.txt) and to lay the groundwork for
markdown versions of the libjpeg-turbo README and build instructions.
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5829cb23
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2012-01-15T00:00:00
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The Independent JPEG Group's JPEG software v8d
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c39ec149
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2011-01-16T00:00:00
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The Independent JPEG Group's JPEG software v8c
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989630f7
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2010-01-10T00:00:00
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The Independent JPEG Group's JPEG software v8
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5996a25e
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2009-06-27T00:00:00
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The Independent JPEG Group's JPEG software v7
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eb32cc1e
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2015-06-25T03:44:36
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Add a new libjpeg API function (jpeg_skip_scanlines()) to allow for partially decoding a JPEG image.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1582 632fc199-4ca6-4c93-a231-07263d6284db
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fced14c7
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2014-05-21T04:13:09
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We don't support non-ANSI C compilers
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1317 632fc199-4ca6-4c93-a231-07263d6284db
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5033f3e1
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2014-05-18T18:33:44
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Remove MS-DOS code and information, and adjust copyright headers to reflect the removal of features in r1307 and r1308. libjpeg-turbo has never supported MS-DOS, nor is it even possible for us to do so.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1312 632fc199-4ca6-4c93-a231-07263d6284db
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da13af6b
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2014-05-18T17:52:06
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Further copyright header cleanup
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1310 632fc199-4ca6-4c93-a231-07263d6284db
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d88f7ddf
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2014-05-18T17:51:00
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Further copyright header cleanup
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.3.x@1309 632fc199-4ca6-4c93-a231-07263d6284db
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52ded876
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2014-05-15T20:30:16
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Remove all of the NEED_SHORT_EXTERNAL_NAMES stuff. There is scant information available as to which linkers ever had a 15-character global symbol name limit. AFAICT, it might have been a VMS and/or a.out BSD thing, but none of those platforms have ever been supported by libjpeg-turbo (nor are such systems supported by other open source libraries of this nature.)
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1307 632fc199-4ca6-4c93-a231-07263d6284db
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05524e67
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2014-05-11T23:14:43
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Document the fact that the fast integer FDCT is not fully accelerated for quality levels above 97 + additional wordsmithing
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.3.x@1289 632fc199-4ca6-4c93-a231-07263d6284db
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8940e6ca
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2014-05-11T09:46:28
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Provide a more thorough description of the trade-offs between the various DCT/IDCT algorithms, based on new resarch
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.3.x@1286 632fc199-4ca6-4c93-a231-07263d6284db
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b7753510
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2014-05-11T09:36:25
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Convert tabs to spaces in the libjpeg code and the SIMD code (TurboJPEG retains the use of tabs for historical reasons. They were annoying in the libjpeg code primarily because they were not consistently used and because they were used to format as well as indent the code. In the case of TurboJPEG, tabs are used just to indent the code, so even if the editor assumes a different tab width, the code will still be readable.)
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.3.x@1285 632fc199-4ca6-4c93-a231-07263d6284db
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e5eaf374
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2014-05-09T18:00:32
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Convert tabs to spaces in the libjpeg code and the SIMD code (TurboJPEG retains the use of tabs for historical reasons. They were annoying in the libjpeg code primarily because they were not consistently used and because they were used to format as well as indent the code. In the case of TurboJPEG, tabs are used just to indent the code, so even if the editor assumes a different tab width, the code will still be readable.)
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1278 632fc199-4ca6-4c93-a231-07263d6284db
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f37e4daf
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2013-01-01T10:52:29
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Port RGB-to-Grayscale color transform from jpeg-8d
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@885 632fc199-4ca6-4c93-a231-07263d6284db
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a73e870a
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2012-12-31T02:52:30
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Change the copyright notices to make it clear that our modified files are not part of the IJG's software.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.2.x@873 632fc199-4ca6-4c93-a231-07263d6284db
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0bfb7805
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2012-12-31T02:42:18
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Change the copyright notices to make it clear that our modified files are not part of the IJG's software.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@872 632fc199-4ca6-4c93-a231-07263d6284db
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760ea8df
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2012-02-07T23:25:19
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Merge documentation and wordsmithing changes from 1.2, including promotion of -arithmetic to a "switch for advanced users"
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.1.x@783 632fc199-4ca6-4c93-a231-07263d6284db
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66a69f04
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2012-01-31T10:19:29
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Incorporate a few upstream doc changes; grammar police; wordsmithing; Move -arithmetic into "switches for advanced users"; Additional documentation for IDCT scaling extensions
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@765 632fc199-4ca6-4c93-a231-07263d6284db
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ccd1bfdd
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2012-01-31T09:53:46
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Incorporate a few upstream doc changes; grammar police; wordsmithing; Move -arithmetic into "switches for advanced users"
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.2.x@764 632fc199-4ca6-4c93-a231-07263d6284db
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27fb3fc5
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2012-01-28T01:48:07
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Support additional scaling factors when decompressing
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@753 632fc199-4ca6-4c93-a231-07263d6284db
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30913542
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2012-01-27T09:53:33
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Be clear that we are only emulating the libjpeg v7/v8 API/ABI, not the library itself.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.2.x@749 632fc199-4ca6-4c93-a231-07263d6284db
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66f97e68
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2010-11-23T05:49:54
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Support arithmetic encoding and decoding
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@299 632fc199-4ca6-4c93-a231-07263d6284db
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39ea562c
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2010-10-12T01:55:31
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Document new v7/v8 features; .doc = .txt
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@252 632fc199-4ca6-4c93-a231-07263d6284db
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