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cnq3/code/libjpeg-turbo/ChangeLog.md
arQon fc9465caab switch from jpeg6 to jpeg-turbo 
aside from the speed improvements, this also makes for nicer code
in the renderer interaction with libjpeg, thanks to mem_dest support etc
2017-01-03 00:34:59 -08:00

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1.5.1

Significant changes relative to 1.5.0:

  1. Previously, the undocumented JSIMD_FORCE* environment variables could be used to force-enable a particular SIMD instruction set if multiple instruction sets were available on a particular platform. On x86 platforms, where CPU feature detection is bulletproof and multiple SIMD instruction sets are available, it makes sense for those environment variables to allow forcing the use of an instruction set only if that instruction set is available. However, since the ARM implementations of libjpeg-turbo can only use one SIMD instruction set, and since their feature detection code is less bulletproof (parsing /proc/cpuinfo), it makes sense for the JSIMD_FORCENEON environment variable to bypass the feature detection code and really force the use of NEON instructions. A new environment variable (JSIMD_FORCEDSPR2) was introduced in the MIPS implementation for the same reasons, and the existing JSIMD_FORCENONE environment variable was extended to that implementation. These environment variables provide a workaround for those attempting to test ARM and MIPS builds of libjpeg-turbo in QEMU, which passes through /proc/cpuinfo from the host system.

  2. libjpeg-turbo previously assumed that AltiVec instructions were always available on PowerPC platforms, which led to "illegal instruction" errors when running on PowerPC chips that lack AltiVec support (such as the older 7xx/G3 and newer e5500 series.) libjpeg-turbo now examines /proc/cpuinfo on Linux/Android systems and enables AltiVec instructions only if the CPU supports them. It also now provides two environment variables, JSIMD_FORCEALTIVEC and JSIMD_FORCENONE, to force-enable and force-disable AltiVec instructions in environments where /proc/cpuinfo is an unreliable means of CPU feature detection (such as when running in QEMU.) On OS X, libjpeg-turbo continues to assume that AltiVec support is always available, which means that libjpeg-turbo cannot be used with G3 Macs unless you set the environment variable JSIMD_FORCENONE to 1.

  3. Fixed an issue whereby 64-bit ARM (AArch64) builds of libjpeg-turbo would crash when built with recent releases of the Clang/LLVM compiler. This was caused by an ABI conformance issue in some of libjpeg-turbo's 64-bit NEON SIMD routines. Those routines were incorrectly using 64-bit instructions to transfer a 32-bit JDIMENSION argument, whereas the ABI allows the upper (unused) 32 bits of a 32-bit argument's register to be undefined. The new Clang/LLVM optimizer uses load combining to transfer multiple adjacent 32-bit structure members into a single 64-bit register, and this exposed the ABI conformance issue.

  4. Fancy upsampling is now supported when decompressing JPEG images that use 4:4:0 (h1v2) chroma subsampling. These images are generated when losslessly rotating or transposing JPEG images that use 4:2:2 (h2v1) chroma subsampling. The h1v2 fancy upsampling algorithm is not currently SIMD-accelerated.

  5. If merged upsampling isn't SIMD-accelerated but YCbCr-to-RGB conversion is, then libjpeg-turbo will now disable merged upsampling when decompressing YCbCr JPEG images into RGB or extended RGB output images. This significantly speeds up the decompression of 4:2:0 and 4:2:2 JPEGs on ARM platforms if fancy upsampling is not used (for example, if the -nosmooth option to djpeg is specified.)

  6. The TurboJPEG API will now decompress 4:2:2 and 4:4:0 JPEG images with 2x2 luminance sampling factors and 2x1 or 1x2 chrominance sampling factors. This is a non-standard way of specifying 2x subsampling (normally 4:2:2 JPEGs have 2x1 luminance and 1x1 chrominance sampling factors, and 4:4:0 JPEGs have 1x2 luminance and 1x1 chrominance sampling factors), but the JPEG specification and the libjpeg API both allow it.

  7. Fixed an unsigned integer overflow in the libjpeg memory manager, detected by the Clang undefined behavior sanitizer, that could be triggered by attempting to decompress a specially-crafted malformed JPEG image. This issue affected only 32-bit code and did not pose a security threat, but removing the warning makes it easier to detect actual security issues, should they arise in the future.

  8. Fixed additional negative left shifts and other issues reported by the GCC and Clang undefined behavior sanitizers when attempting to decompress specially-crafted malformed JPEG images. None of these issues posed a security threat, but removing the warnings makes it easier to detect actual security issues, should they arise in the future.

  9. Fixed an out-of-bounds array reference, introduced by 1.4.90[2] (partial image decompression) and detected by the Clang undefined behavior sanitizer, that could be triggered by a specially-crafted malformed JPEG image with more than four components. Because the out-of-bounds reference was still within the same structure, it was not known to pose a security threat, but removing the warning makes it easier to detect actual security issues, should they arise in the future.

  10. Fixed another ABI conformance issue in the 64-bit ARM (AArch64) NEON SIMD code. Some of the routines were incorrectly reading and storing data below the stack pointer, which caused segfaults in certain applications under specific circumstances.

1.5.0

Significant changes relative to 1.5 beta1:

  1. Fixed an issue whereby a malformed motion-JPEG frame could cause the "fast path" of libjpeg-turbo's Huffman decoder to read from uninitialized memory.

  2. Added libjpeg-turbo version and build information to the global string table of the libjpeg and TurboJPEG API libraries. This is a common practice in other infrastructure libraries, such as OpenSSL and libpng, because it makes it easy to examine an application binary and determine which version of the library the application was linked against.

  3. Fixed a couple of issues in the PPM reader that would cause buffer overruns in cjpeg if one of the values in a binary PPM/PGM input file exceeded the maximum value defined in the file's header. libjpeg-turbo 1.4.2 already included a similar fix for ASCII PPM/PGM files. Note that these issues were not security bugs, since they were confined to the cjpeg program and did not affect any of the libjpeg-turbo libraries.

  4. Fixed an issue whereby attempting to decompress a JPEG file with a corrupt header using the tjDecompressToYUV2() function would cause the function to abort without returning an error and, under certain circumstances, corrupt the stack. This only occurred if tjDecompressToYUV2() was called prior to calling tjDecompressHeader3(), or if the return value from tjDecompressHeader3() was ignored (both cases represent incorrect usage of the TurboJPEG API.)

  5. Fixed an issue in the ARM 32-bit SIMD-accelerated Huffman encoder that prevented the code from assembling properly with clang.

  6. The jpeg_stdio_src(), jpeg_mem_src(), jpeg_stdio_dest(), and jpeg_mem_dest() functions in the libjpeg API will now throw an error if a source/destination manager has already been assigned to the compress or decompress object by a different function or by the calling program. This prevents these functions from attempting to reuse a source/destination manager structure that was allocated elsewhere, because there is no way to ensure that it would be big enough to accommodate the new source/destination manager.

1.4.90 (1.5 beta1)

Significant changes relative to 1.4.2:

  1. Added full SIMD acceleration for PowerPC platforms using AltiVec VMX (128-bit SIMD) instructions. Although the performance of libjpeg-turbo on PowerPC was already good, due to the increased number of registers available to the compiler vs. x86, it was still possible to speed up compression by about 3-4x and decompression by about 2-2.5x (relative to libjpeg v6b) through the use of AltiVec instructions.

  2. Added two new libjpeg API functions (jpeg_skip_scanlines() and jpeg_crop_scanline()) that can be used to partially decode a JPEG image. See libjpeg.txt for more details.

  3. The TJCompressor and TJDecompressor classes in the TurboJPEG Java API now implement the Closeable interface, so those classes can be used with a try-with-resources statement.

  4. The TurboJPEG Java classes now throw unchecked idiomatic exceptions (IllegalArgumentException, IllegalStateException) for unrecoverable errors caused by incorrect API usage, and those classes throw a new checked exception type (TJException) for errors that are passed through from the C library.

  5. Source buffers for the TurboJPEG C API functions, as well as the jpeg_mem_src() function in the libjpeg API, are now declared as const pointers. This facilitates passing read-only buffers to those functions and ensures the caller that the source buffer will not be modified. This should not create any backward API or ABI incompatibilities with prior libjpeg-turbo releases.

  6. The MIPS DSPr2 SIMD code can now be compiled to support either FR=0 or FR=1 FPUs.

  7. Fixed additional negative left shifts and other issues reported by the GCC and Clang undefined behavior sanitizers. Most of these issues affected only 32-bit code, and none of them was known to pose a security threat, but removing the warnings makes it easier to detect actual security issues, should they arise in the future.

  8. Removed the unnecessary .arch directive from the ARM64 NEON SIMD code. This directive was preventing the code from assembling using the clang integrated assembler.

  9. Fixed a regression caused by 1.4.1[6] that prevented 32-bit and 64-bit libjpeg-turbo RPMs from being installed simultaneously on recent Red Hat/Fedora distributions. This was due to the addition of a macro in jconfig.h that allows the Huffman codec to determine the word size at compile time. Since that macro differs between 32-bit and 64-bit builds, this caused a conflict between the i386 and x86_64 RPMs (any differing files, other than executables, are not allowed when 32-bit and 64-bit RPMs are installed simultaneously.) Since the macro is used only internally, it has been moved into jconfigint.h.

  10. The x86-64 SIMD code can now be disabled at run time by setting the JSIMD_FORCENONE environment variable to 1 (the other SIMD implementations already had this capability.)

  11. Added a new command-line argument to TJBench (-nowrite) that prevents the benchmark from outputting any images. This removes any potential operating system overhead that might be caused by lazy writes to disk and thus improves the consistency of the performance measurements.

  12. Added SIMD acceleration for Huffman encoding on SSE2-capable x86 and x86-64 platforms. This speeds up the compression of full-color JPEGs by about 10-15% on average (relative to libjpeg-turbo 1.4.x) when using modern Intel and AMD CPUs. Additionally, this works around an issue in the clang optimizer that prevents it (as of this writing) from achieving the same performance as GCC when compiling the C version of the Huffman encoder (https://llvm.org/bugs/show_bug.cgi?id=16035). For the purposes of benchmarking or regression testing, SIMD-accelerated Huffman encoding can be disabled by setting the JSIMD_NOHUFFENC environment variable to 1.

  13. Added ARM 64-bit (ARMv8) NEON SIMD implementations of the commonly-used compression algorithms (including the slow integer forward DCT and h2v2 & h2v1 downsampling algorithms, which are not accelerated in the 32-bit NEON implementation.) This speeds up the compression of full-color JPEGs by about 75% on average on a Cavium ThunderX processor and by about 2-2.5x on average on Cortex-A53 and Cortex-A57 cores.

  14. Added SIMD acceleration for Huffman encoding on NEON-capable ARM 32-bit and 64-bit platforms.

    For 32-bit code, this speeds up the compression of full-color JPEGs by about 30% on average on a typical iOS device (iPhone 4S, Cortex-A9) and by about 6-7% on average on a typical Android device (Nexus 5X, Cortex-A53 and Cortex-A57), relative to libjpeg-turbo 1.4.x. Note that the larger speedup under iOS is due to the fact that iOS builds use LLVM, which does not optimize the C Huffman encoder as well as GCC does.

    For 64-bit code, NEON-accelerated Huffman encoding speeds up the compression of full-color JPEGs by about 40% on average on a typical iOS device (iPhone 5S, Apple A7) and by about 7-8% on average on a typical Android device (Nexus 5X, Cortex-A53 and Cortex-A57), in addition to the speedup described in [13] above.

    For the purposes of benchmarking or regression testing, SIMD-accelerated Huffman encoding can be disabled by setting the JSIMD_NOHUFFENC environment variable to 1.

  15. pkg-config (.pc) scripts are now included for both the libjpeg and TurboJPEG API libraries on Un*x systems. Note that if a project's build system relies on these scripts, then it will not be possible to build that project with libjpeg or with a prior version of libjpeg-turbo.

  16. Optimized the ARM 64-bit (ARMv8) NEON SIMD decompression routines to improve performance on CPUs with in-order pipelines. This speeds up the decompression of full-color JPEGs by nearly 2x on average on a Cavium ThunderX processor and by about 15% on average on a Cortex-A53 core.

  17. Fixed an issue in the accelerated Huffman decoder that could have caused the decoder to read past the end of the input buffer when a malformed, specially-crafted JPEG image was being decompressed. In prior versions of libjpeg-turbo, the accelerated Huffman decoder was invoked (in most cases) only if there were > 128 bytes of data in the input buffer. However, it is possible to construct a JPEG image in which a single Huffman block is over 430 bytes long, so this version of libjpeg-turbo activates the accelerated Huffman decoder only if there are > 512 bytes of data in the input buffer.

  18. Fixed a memory leak in tjunittest encountered when running the program with the -yuv option.

1.4.2

Significant changes relative to 1.4.1:

  1. Fixed an issue whereby cjpeg would segfault if a Windows bitmap with a negative width or height was used as an input image (Windows bitmaps can have a negative height if they are stored in top-down order, but such files are rare and not supported by libjpeg-turbo.)

  2. Fixed an issue whereby, under certain circumstances, libjpeg-turbo would incorrectly encode certain JPEG images when quality=100 and the fast integer forward DCT were used. This was known to cause make test to fail when the library was built with -march=haswell on x86 systems.

  3. Fixed an issue whereby libjpeg-turbo would crash when built with the latest & greatest development version of the Clang/LLVM compiler. This was caused by an x86-64 ABI conformance issue in some of libjpeg-turbo's 64-bit SSE2 SIMD routines. Those routines were incorrectly using a 64-bit mov instruction to transfer a 32-bit JDIMENSION argument, whereas the x86-64 ABI allows the upper (unused) 32 bits of a 32-bit argument's register to be undefined. The new Clang/LLVM optimizer uses load combining to transfer multiple adjacent 32-bit structure members into a single 64-bit register, and this exposed the ABI conformance issue.

  4. Fixed a bug in the MIPS DSPr2 4:2:0 "plain" (non-fancy and non-merged) upsampling routine that caused a buffer overflow (and subsequent segfault) when decompressing a 4:2:0 JPEG image whose scaled output width was less than 16 pixels. The "plain" upsampling routines are normally only used when decompressing a non-YCbCr JPEG image, but they are also used when decompressing a JPEG image whose scaled output height is 1.

  5. Fixed various negative left shifts and other issues reported by the GCC and Clang undefined behavior sanitizers. None of these was known to pose a security threat, but removing the warnings makes it easier to detect actual security issues, should they arise in the future.

1.4.1

Significant changes relative to 1.4.0:

  1. tjbench now properly handles CMYK/YCCK JPEG files. Passing an argument of -cmyk (instead of, for instance, -rgb) will cause tjbench to internally convert the source bitmap to CMYK prior to compression, to generate YCCK JPEG files, and to internally convert the decompressed CMYK pixels back to RGB after decompression (the latter is done automatically if a CMYK or YCCK JPEG is passed to tjbench as a source image.) The CMYK<->RGB conversion operation is not benchmarked. NOTE: The quick & dirty CMYK<->RGB conversions that tjbench uses are suitable for testing only. Proper conversion between CMYK and RGB requires a color management system.

  2. make test now performs additional bitwise regression tests using tjbench, mainly for the purpose of testing compression from/decompression to a subregion of a larger image buffer.

  3. make test no longer tests the regression of the floating point DCT/IDCT by default, since the results of those tests can vary if the algorithms in question are not implemented using SIMD instructions on a particular platform. See the comments in Makefile.am for information on how to re-enable the tests and to specify an expected result for them based on the particulars of your platform.

  4. The NULL color conversion routines have been significantly optimized, which speeds up the compression of RGB and CMYK JPEGs by 5-20% when using 64-bit code and 0-3% when using 32-bit code, and the decompression of those images by 10-30% when using 64-bit code and 3-12% when using 32-bit code.

  5. Fixed an "illegal instruction" error that occurred when djpeg from a SIMD-enabled libjpeg-turbo MIPS build was executed with the -nosmooth option on a MIPS machine that lacked DSPr2 support. The MIPS SIMD routines for h2v1 and h2v2 merged upsampling were not properly checking for the existence of DSPr2.

  6. Performance has been improved significantly on 64-bit non-Linux and non-Windows platforms (generally 10-20% faster compression and 5-10% faster decompression.) Due to an oversight, the 64-bit version of the accelerated Huffman codec was not being compiled in when libjpeg-turbo was built on platforms other than Windows or Linux. Oops.

  7. Fixed an extremely rare bug in the Huffman encoder that caused 64-bit builds of libjpeg-turbo to incorrectly encode a few specific test images when quality=98, an optimized Huffman table, and the slow integer forward DCT were used.

  8. The Windows (CMake) build system now supports building only static or only shared libraries. This is accomplished by adding either -DENABLE_STATIC=0 or -DENABLE_SHARED=0 to the CMake command line.

  9. TurboJPEG API functions will now return an error code if a warning is triggered in the underlying libjpeg API. For instance, if a JPEG file is corrupt, the TurboJPEG decompression functions will attempt to decompress as much of the image as possible, but those functions will now return -1 to indicate that the decompression was not entirely successful.

  10. Fixed a bug in the MIPS DSPr2 4:2:2 fancy upsampling routine that caused a buffer overflow (and subsequent segfault) when decompressing a 4:2:2 JPEG image in which the right-most MCU was 5 or 6 pixels wide.

1.4.0

Significant changes relative to 1.4 beta1:

  1. Fixed a build issue on OS X PowerPC platforms (md5cmp failed to build because OS X does not provide the le32toh() and htole32() functions.)

  2. The non-SIMD RGB565 color conversion code did not work correctly on big endian machines. This has been fixed.

  3. Fixed an issue in tjPlaneSizeYUV() whereby it would erroneously return 1 instead of -1 if componentID was > 0 and subsamp was TJSAMP_GRAY.

  4. Fixed an issue in tjBufSizeYUV2() whereby it would erroneously return 0 instead of -1 if width was < 1.

  5. The Huffman encoder now uses clz and bsr instructions for bit counting on ARM64 platforms (see 1.4 beta1[5].)

  6. The close() method in the TJCompressor and TJDecompressor Java classes is now idempotent. Previously, that method would call the native tjDestroy() function even if the TurboJPEG instance had already been destroyed. This caused an exception to be thrown during finalization, if the close() method had already been called. The exception was caught, but it was still an expensive operation.

  7. The TurboJPEG API previously generated an error (Could not determine subsampling type for JPEG image) when attempting to decompress grayscale JPEG images that were compressed with a sampling factor other than 1 (for instance, with cjpeg -grayscale -sample 2x2). Subsampling technically has no meaning with grayscale JPEGs, and thus the horizontal and vertical sampling factors for such images are ignored by the decompressor. However, the TurboJPEG API was being too rigid and was expecting the sampling factors to be equal to 1 before it treated the image as a grayscale JPEG.

  8. cjpeg, djpeg, and jpegtran now accept an argument of -version, which will print the library version and exit.

  9. Referring to 1.4 beta1[15], another extremely rare circumstance was discovered under which the Huffman encoder's local buffer can be overrun when a buffered destination manager is being used and an extremely-high-frequency block (basically junk image data) is being encoded. Even though the Huffman local buffer was increased from 128 bytes to 136 bytes to address the previous issue, the new issue caused even the larger buffer to be overrun. Further analysis reveals that, in the absolute worst case (such as setting alternating AC coefficients to 32767 and -32768 in the JPEG scanning order), the Huffman encoder can produce encoded blocks that approach double the size of the unencoded blocks. Thus, the Huffman local buffer was increased to 256 bytes, which should prevent any such issue from re-occurring in the future.

  10. The new tjPlaneSizeYUV(), tjPlaneWidth(), and tjPlaneHeight() functions were not actually usable on any platform except OS X and Windows, because those functions were not included in the libturbojpeg mapfile. This has been fixed.

  11. Restored the JPP(), JMETHOD(), and FAR macros in the libjpeg-turbo header files. The JPP() and JMETHOD() macros were originally implemented in libjpeg as a way of supporting non-ANSI compilers that lacked support for prototype parameters. libjpeg-turbo has never supported such compilers, but some software packages still use the macros to define their own prototypes. Similarly, libjpeg-turbo has never supported MS-DOS and other platforms that have far symbols, but some software packages still use the FAR macro. A pretty good argument can be made that this is a bad practice on the part of the software in question, but since this affects more than one package, it's just easier to fix it here.

  12. Fixed issues that were preventing the ARM 64-bit SIMD code from compiling for iOS, and included an ARMv8 architecture in all of the binaries installed by the "official" libjpeg-turbo SDK for OS X.

1.3.90 (1.4 beta1)

Significant changes relative to 1.3.1:

  1. New features in the TurboJPEG API:

    • YUV planar images can now be generated with an arbitrary line padding (previously only 4-byte padding, which was compatible with X Video, was supported.)
    • The decompress-to-YUV function has been extended to support image scaling.
    • JPEG images can now be compressed from YUV planar source images.
    • YUV planar images can now be decoded into RGB or grayscale images.
    • 4:1:1 subsampling is now supported. This is mainly included for compatibility, since 4:1:1 is not fully accelerated in libjpeg-turbo and has no significant advantages relative to 4:2:0.
    • CMYK images are now supported. This feature allows CMYK source images to be compressed to YCCK JPEGs and YCCK or CMYK JPEGs to be decompressed to CMYK destination images. Conversion between CMYK/YCCK and RGB or YUV images is not supported. Such conversion requires a color management system and is thus out of scope for a codec library.
    • The handling of YUV images in the Java API has been significantly refactored and should now be much more intuitive.
    • The Java API now supports encoding a YUV image from an arbitrary position in a large image buffer.
    • All of the YUV functions now have a corresponding function that operates on separate image planes instead of a unified image buffer. This allows for compressing/decoding from or decompressing/encoding to a subregion of a larger YUV image. It also allows for handling YUV formats that swap the order of the U and V planes.

  2. Added SIMD acceleration for DSPr2-capable MIPS platforms. This speeds up the compression of full-color JPEGs by 70-80% on such platforms and decompression by 25-35%.

  3. If an application attempts to decompress a Huffman-coded JPEG image whose header does not contain Huffman tables, libjpeg-turbo will now insert the default Huffman tables. In order to save space, many motion JPEG video frames are encoded without the default Huffman tables, so these frames can now be successfully decompressed by libjpeg-turbo without additional work on the part of the application. An application can still override the Huffman tables, for instance to re-use tables from a previous frame of the same video.

  4. The Mac packaging system now uses pkgbuild and productbuild rather than PackageMaker (which is obsolete and no longer supported.) This means that OS X 10.6 "Snow Leopard" or later must be used when packaging libjpeg-turbo, although the packages produced can be installed on OS X 10.5 "Leopard" or later. OS X 10.4 "Tiger" is no longer supported.

  5. The Huffman encoder now uses clz and bsr instructions for bit counting on ARM platforms rather than a lookup table. This reduces the memory footprint by 64k, which may be important for some mobile applications. Out of four Android devices that were tested, two demonstrated a small overall performance loss (~3-4% on average) with ARMv6 code and a small gain (also ~3-4%) with ARMv7 code when enabling this new feature, but the other two devices demonstrated a significant overall performance gain with both ARMv6 and ARMv7 code (~10-20%) when enabling the feature. Actual mileage may vary.

  6. Worked around an issue with Visual C++ 2010 and later that caused incorrect pixels to be generated when decompressing a JPEG image to a 256-color bitmap, if compiler optimization was enabled when libjpeg-turbo was built. This caused the regression tests to fail when doing a release build under Visual C++ 2010 and later.

  7. Improved the accuracy and performance of the non-SIMD implementation of the floating point inverse DCT (using code borrowed from libjpeg v8a and later.) The accuracy of this implementation now matches the accuracy of the SSE/SSE2 implementation. Note, however, that the floating point DCT/IDCT algorithms are mainly a legacy feature. They generally do not produce significantly better accuracy than the slow integer DCT/IDCT algorithms, and they are quite a bit slower.

  8. Added a new output colorspace (JCS_RGB565) to the libjpeg API that allows for decompressing JPEG images into RGB565 (16-bit) pixels. If dithering is not used, then this code path is SIMD-accelerated on ARM platforms.

  9. Numerous obsolete features, such as support for non-ANSI compilers and support for the MS-DOS memory model, were removed from the libjpeg code, greatly improving its readability and making it easier to maintain and extend.

  10. Fixed a segfault that occurred when calling output_message() with msg_code set to JMSG_COPYRIGHT.

  11. Fixed an issue whereby wrjpgcom was allowing comments longer than 65k characters to be passed on the command line, which was causing it to generate incorrect JPEG files.

  12. Fixed a bug in the build system that was causing the Windows version of wrjpgcom to be built using the rdjpgcom source code.

  13. Restored 12-bit-per-component JPEG support. A 12-bit version of libjpeg-turbo can now be built by passing an argument of --with-12bit to configure (Unix) or -DWITH_12BIT=1 to cmake (Windows.) 12-bit JPEG support is included only for convenience. Enabling this feature disables all of the performance features in libjpeg-turbo, as well as arithmetic coding and the TurboJPEG API. The resulting library still contains the other libjpeg-turbo features (such as the colorspace extensions), but in general, it performs no faster than libjpeg v6b.

  14. Added ARM 64-bit SIMD acceleration for the YCC-to-RGB color conversion and IDCT algorithms (both are used during JPEG decompression.) For unknown reasons (probably related to clang), this code cannot currently be compiled for iOS.

  15. Fixed an extremely rare bug that could cause the Huffman encoder's local buffer to overrun when a very high-frequency MCU is compressed using quality 100 and no subsampling, and when the JPEG output buffer is being dynamically resized by the destination manager. This issue was so rare that, even with a test program specifically designed to make the bug occur (by injecting random high-frequency YUV data into the compressor), it was reproducible only once in about every 25 million iterations.

  16. Fixed an oversight in the TurboJPEG C wrapper: if any of the JPEG compression functions was called repeatedly with the same automatically-allocated destination buffer, then TurboJPEG would erroneously assume that the jpegSize parameter was equal to the size of the buffer, when in fact that parameter was probably equal to the size of the most recently compressed JPEG image. If the size of the previous JPEG image was not as large as the current JPEG image, then TurboJPEG would unnecessarily reallocate the destination buffer.

1.3.1

Significant changes relative to 1.3.0:

  1. On Un*x systems, make install now installs the libjpeg-turbo libraries into /opt/libjpeg-turbo/lib32 by default on any 32-bit system, not just x86, and into /opt/libjpeg-turbo/lib64 by default on any 64-bit system, not just x86-64. You can override this by overriding either the prefix or libdir configure variables.

  2. The Windows installer now places a copy of the TurboJPEG DLLs in the same directory as the rest of the libjpeg-turbo binaries. This was mainly done to support TurboVNC 1.3, which bundles the DLLs in its Windows installation. When using a 32-bit version of CMake on 64-bit Windows, it is impossible to access the c:\WINDOWS\system32 directory, which made it impossible for the TurboVNC build scripts to bundle the 64-bit TurboJPEG DLL.

  3. Fixed a bug whereby attempting to encode a progressive JPEG with arithmetic entropy coding (by passing arguments of -progressive -arithmetic to cjpeg or jpegtran, for instance) would result in an error, Requested feature was omitted at compile time.

  4. Fixed a couple of issues whereby malformed JPEG images would cause libjpeg-turbo to use uninitialized memory during decompression.

  5. Fixed an error (Buffer passed to JPEG library is too small) that occurred when calling the TurboJPEG YUV encoding function with a very small (< 5x5) source image, and added a unit test to check for this error.

  6. The Java classes should now build properly under Visual Studio 2010 and later.

  7. Fixed an issue that prevented SRPMs generated using the in-tree packaging tools from being rebuilt on certain newer Linux distributions.

  8. Numerous minor fixes to eliminate compilation and build/packaging system warnings, fix cosmetic issues, improve documentation clarity, and other general source cleanup.

1.3.0

Significant changes relative to 1.3 beta1:

  1. make test now works properly on FreeBSD, and it no longer requires the md5sum executable to be present on other Un*x platforms.

  2. Overhauled the packaging system:

    • To avoid conflict with vendor-supplied libjpeg-turbo packages, the official RPMs and DEBs for libjpeg-turbo have been renamed to "libjpeg-turbo-official".
    • The TurboJPEG libraries are now located under /opt/libjpeg-turbo in the official Linux and Mac packages, to avoid conflict with vendor-supplied packages and also to streamline the packaging system.
    • Release packages are now created with the directory structure defined by the configure variables prefix, bindir, libdir, etc. (Un*x) or by the CMAKE_INSTALL_PREFIX variable (Windows.) The exception is that the docs are always located under the system default documentation directory on Un*x and Mac systems, and on Windows, the TurboJPEG DLL is always located in the Windows system directory.
    • To avoid confusion, official libjpeg-turbo packages on Linux/Unix platforms (except for Mac) will always install the 32-bit libraries in /opt/libjpeg-turbo/lib32 and the 64-bit libraries in /opt/libjpeg-turbo/lib64.
    • Fixed an issue whereby, in some cases, the libjpeg-turbo executables on Un*x systems were not properly linking with the shared libraries installed by the same package.
    • Fixed an issue whereby building the "installer" target on Windows when WITH_JAVA=1 would fail if the TurboJPEG JAR had not been previously built.
    • Building the "install" target on Windows now installs files into the same places that the installer does.

  3. Fixed a Huffman encoder bug that prevented I/O suspension from working properly.

1.2.90 (1.3 beta1)

Significant changes relative to 1.2.1:

  1. Added support for additional scaling factors (3/8, 5/8, 3/4, 7/8, 9/8, 5/4, 11/8, 3/2, 13/8, 7/4, 15/8, and 2) when decompressing. Note that the IDCT will not be SIMD-accelerated when using any of these new scaling factors.

  2. The TurboJPEG dynamic library is now versioned. It was not strictly necessary to do so, because TurboJPEG uses versioned symbols, and if a function changes in an ABI-incompatible way, that function is renamed and a legacy function is provided to maintain backward compatibility. However, certain Linux distro maintainers have a policy against accepting any library that isn't versioned.

  3. Extended the TurboJPEG Java API so that it can be used to compress a JPEG image from and decompress a JPEG image to an arbitrary position in a large image buffer.

  4. The tjDecompressToYUV() function now supports the TJFLAG_FASTDCT flag.

  5. The 32-bit supplementary package for amd64 Debian systems now provides symlinks in /usr/lib/i386-linux-gnu for the TurboJPEG libraries in /usr/lib32. This allows those libraries to be used on MultiArch-compatible systems (such as Ubuntu 11 and later) without setting the linker path.

  6. The TurboJPEG Java wrapper should now find the JNI library on Mac systems without having to pass -Djava.library.path=/usr/lib to java.

  7. TJBench has been ported to Java to provide a convenient way of validating the performance of the TurboJPEG Java API. It can be run with java -cp turbojpeg.jar TJBench.

  8. cjpeg can now be used to generate JPEG files with the RGB colorspace (feature ported from jpeg-8d.)

  9. The width and height in the -crop argument passed to jpegtran can now be suffixed with f to indicate that, when the upper left corner of the cropping region is automatically moved to the nearest iMCU boundary, the bottom right corner should be moved by the same amount. In other words, this feature causes jpegtran to strictly honor the specified width/height rather than the specified bottom right corner (feature ported from jpeg-8d.)

  10. JPEG files using the RGB colorspace can now be decompressed into grayscale images (feature ported from jpeg-8d.)

  11. Fixed a regression caused by 1.2.1[7] whereby the build would fail with multiple "Mismatch in operand sizes" errors when attempting to build the x86 SIMD code with NASM 0.98.

  12. The in-memory source/destination managers (jpeg_mem_src() and jpeg_mem_dest()) are now included by default when building libjpeg-turbo with libjpeg v6b or v7 emulation, so that programs can take advantage of these functions without requiring the use of the backward-incompatible libjpeg v8 ABI. The "age number" of the libjpeg-turbo library on Un*x systems has been incremented by 1 to reflect this. You can disable this feature with a configure/CMake switch in order to retain strict API/ABI compatibility with the libjpeg v6b or v7 API/ABI (or with previous versions of libjpeg-turbo.) See README.md for more details.

  13. Added ARMv7s architecture to libjpeg.a and libturbojpeg.a in the official libjpeg-turbo binary package for OS X, so that those libraries can be used to build applications that leverage the faster CPUs in the iPhone 5 and iPad 4.

1.2.1

Significant changes relative to 1.2.0:

  1. Creating or decoding a JPEG file that uses the RGB colorspace should now properly work when the input or output colorspace is one of the libjpeg-turbo colorspace extensions.

  2. When libjpeg-turbo was built without SIMD support and merged (non-fancy) upsampling was used along with an alpha-enabled colorspace during decompression, the unused byte of the decompressed pixels was not being set to 0xFF. This has been fixed. TJUnitTest has also been extended to test for the correct behavior of the colorspace extensions when merged upsampling is used.

  3. Fixed a bug whereby the libjpeg-turbo SSE2 SIMD code would not preserve the upper 64 bits of xmm6 and xmm7 on Win64 platforms, which violated the Win64 calling conventions.

  4. Fixed a regression caused by 1.2.0[6] whereby decompressing corrupt JPEG images (specifically, images in which the component count was erroneously set to a large value) would cause libjpeg-turbo to segfault.

  5. Worked around a severe performance issue with "Bobcat" (AMD Embedded APU) processors. The MASKMOVDQU instruction, which was used by the libjpeg-turbo SSE2 SIMD code, is apparently implemented in microcode on AMD processors, and it is painfully slow on Bobcat processors in particular. Eliminating the use of this instruction improved performance by an order of magnitude on Bobcat processors and by a small amount (typically 5%) on AMD desktop processors.

  6. Added SIMD acceleration for performing 4:2:2 upsampling on NEON-capable ARM platforms. This speeds up the decompression of 4:2:2 JPEGs by 20-25% on such platforms.

  7. Fixed a regression caused by 1.2.0[2] whereby, on Linux/x86 platforms running the 32-bit SSE2 SIMD code in libjpeg-turbo, decompressing a 4:2:0 or 4:2:2 JPEG image into a 32-bit (RGBX, BGRX, etc.) buffer without using fancy upsampling would produce several incorrect columns of pixels at the right-hand side of the output image if each row in the output image was not evenly divisible by 16 bytes.

  8. Fixed an issue whereby attempting to build the SIMD extensions with Xcode 4.3 on OS X platforms would cause NASM to return numerous errors of the form "'%define' expects a macro identifier".

  9. Added flags to the TurboJPEG API that allow the caller to force the use of either the fast or the accurate DCT/IDCT algorithms in the underlying codec.

1.2.0

Significant changes relative to 1.2 beta1:

  1. Fixed build issue with YASM on Unix systems (the libjpeg-turbo build system was not adding the current directory to the assembler include path, so YASM was not able to find jsimdcfg.inc.)

  2. Fixed out-of-bounds read in SSE2 SIMD code that occurred when decompressing a JPEG image to a bitmap buffer whose size was not a multiple of 16 bytes. This was more of an annoyance than an actual bug, since it did not cause any actual run-time problems, but the issue showed up when running libjpeg-turbo in valgrind. See http://crbug.com/72399 for more information.

  3. Added a compile-time macro (LIBJPEG_TURBO_VERSION) that can be used to check the version of libjpeg-turbo against which an application was compiled.

  4. Added new RGBA/BGRA/ABGR/ARGB colorspace extension constants (libjpeg API) and pixel formats (TurboJPEG API), which allow applications to specify that, when decompressing to a 4-component RGB buffer, the unused byte should be set to 0xFF so that it can be interpreted as an opaque alpha channel.

  5. Fixed regression issue whereby DevIL failed to build against libjpeg-turbo because libjpeg-turbo's distributed version of jconfig.h contained an INLINE macro, which conflicted with a similar macro in DevIL. This macro is used only internally when building libjpeg-turbo, so it was moved into config.h.

  6. libjpeg-turbo will now correctly decompress erroneous CMYK/YCCK JPEGs whose K component is assigned a component ID of 1 instead of 4. Although these files are in violation of the spec, other JPEG implementations handle them correctly.

  7. Added ARMv6 and ARMv7 architectures to libjpeg.a and libturbojpeg.a in the official libjpeg-turbo binary package for OS X, so that those libraries can be used to build both OS X and iOS applications.

1.1.90 (1.2 beta1)

Significant changes relative to 1.1.1:

  1. Added a Java wrapper for the TurboJPEG API. See java/README for more details.

  2. The TurboJPEG API can now be used to scale down images during decompression.

  3. Added SIMD routines for RGB-to-grayscale color conversion, which significantly improves the performance of grayscale JPEG compression from an RGB source image.

  4. Improved the performance of the C color conversion routines, which are used on platforms for which SIMD acceleration is not available.

  5. Added a function to the TurboJPEG API that performs lossless transforms. This function is implemented using the same back end as jpegtran, but it performs transcoding entirely in memory and allows multiple transforms and/or crop operations to be batched together, so the source coefficients only need to be read once. This is useful when generating image tiles from a single source JPEG.

  6. Added tests for the new TurboJPEG scaled decompression and lossless transform features to tjbench (the TurboJPEG benchmark, formerly called "jpgtest".)

  7. Added support for 4:4:0 (transposed 4:2:2) subsampling in TurboJPEG, which was necessary in order for it to read 4:2:2 JPEG files that had been losslessly transposed or rotated 90 degrees.

  8. All legacy VirtualGL code has been re-factored, and this has allowed libjpeg-turbo, in its entirety, to be re-licensed under a BSD-style license.

  9. libjpeg-turbo can now be built with YASM.

  10. Added SIMD acceleration for ARM Linux and iOS platforms that support NEON instructions.

  11. Refactored the TurboJPEG C API and documented it using Doxygen. The TurboJPEG 1.2 API uses pixel formats to define the size and component order of the uncompressed source/destination images, and it includes a more efficient version of TJBUFSIZE() that computes a worst-case JPEG size based on the level of chrominance subsampling. The refactored implementation of the TurboJPEG API now uses the libjpeg memory source and destination managers, which allows the TurboJPEG compressor to grow the JPEG buffer as necessary.

  12. Eliminated errors in the output of jpegtran on Windows that occurred when the application was invoked using I/O redirection (jpegtran <input.jpg >output.jpg.)

  13. The inclusion of libjpeg v7 and v8 emulation as well as arithmetic coding support in libjpeg-turbo v1.1.0 introduced several new error constants in jerror.h, and these were mistakenly enabled for all emulation modes, causing the error enum in libjpeg-turbo to sometimes have different values than the same enum in libjpeg. This represents an ABI incompatibility, and it caused problems with rare applications that took specific action based on a particular error value. The fix was to include the new error constants conditionally based on whether libjpeg v7 or v8 emulation was enabled.

  14. Fixed an issue whereby Windows applications that used libjpeg-turbo would fail to compile if the Windows system headers were included before jpeglib.h. This issue was caused by a conflict in the definition of the INT32 type.

  15. Fixed 32-bit supplementary package for amd64 Debian systems, which was broken by enhancements to the packaging system in 1.1.

  16. When decompressing a JPEG image using an output colorspace of JCS_EXT_RGBX, JCS_EXT_BGRX, JCS_EXT_XBGR, or JCS_EXT_XRGB, libjpeg-turbo will now set the unused byte to 0xFF, which allows applications to interpret that byte as an alpha channel (0xFF = opaque).

1.1.1

Significant changes relative to 1.1.0:

  1. Fixed a 1-pixel error in row 0, column 21 of the luminance plane generated by tjEncodeYUV().

  2. libjpeg-turbo's accelerated Huffman decoder previously ignored unexpected markers found in the middle of the JPEG data stream during decompression. It will now hand off decoding of a particular block to the unaccelerated Huffman decoder if an unexpected marker is found, so that the unaccelerated Huffman decoder can generate an appropriate warning.

  3. Older versions of MinGW64 prefixed symbol names with underscores by default, which differed from the behavior of 64-bit Visual C++. MinGW64 1.0 has adopted the behavior of 64-bit Visual C++ as the default, so to accommodate this, the libjpeg-turbo SIMD function names are no longer prefixed with an underscore when building with MinGW64. This means that, when building libjpeg-turbo with older versions of MinGW64, you will now have to add -fno-leading-underscore to the CFLAGS.

  4. Fixed a regression bug in the NSIS script that caused the Windows installer build to fail when using the Visual Studio IDE.

  5. Fixed a bug in jpeg_read_coefficients() whereby it would not initialize cinfo->image_width and cinfo->image_height if libjpeg v7 or v8 emulation was enabled. This specifically caused the jpegoptim program to fail if it was linked against a version of libjpeg-turbo that was built with libjpeg v7 or v8 emulation.

  6. Eliminated excessive I/O overhead that occurred when reading BMP files in cjpeg.

  7. Eliminated errors in the output of cjpeg on Windows that occurred when the application was invoked using I/O redirection (cjpeg <inputfile >output.jpg.)

1.1.0

Significant changes relative to 1.1 beta1:

  1. The algorithm used by the SIMD quantization function cannot produce correct results when the JPEG quality is >= 98 and the fast integer forward DCT is used. Thus, the non-SIMD quantization function is now used for those cases, and libjpeg-turbo should now produce identical output to libjpeg v6b in all cases.

  2. Despite the above, the fast integer forward DCT still degrades somewhat for JPEG qualities greater than 95, so the TurboJPEG wrapper will now automatically use the slow integer forward DCT when generating JPEG images of quality 96 or greater. This reduces compression performance by as much as 15% for these high-quality images but is necessary to ensure that the images are perceptually lossless. It also ensures that the library can avoid the performance pitfall created by [1].

  3. Ported jpgtest.cxx to pure C to avoid the need for a C++ compiler.

  4. Fixed visual artifacts in grayscale JPEG compression caused by a typo in the RGB-to-luminance lookup tables.

  5. The Windows distribution packages now include the libjpeg run-time programs (cjpeg, etc.)

  6. All packages now include jpgtest.

  7. The TurboJPEG dynamic library now uses versioned symbols.

  8. Added two new TurboJPEG API functions, tjEncodeYUV() and tjDecompressToYUV(), to replace the somewhat hackish TJ_YUV flag.

1.0.90 (1.1 beta1)

Significant changes relative to 1.0.1:

  1. Added emulation of the libjpeg v7 and v8 APIs and ABIs. See README.md for more details. This feature was sponsored by CamTrace SAS.

  2. Created a new CMake-based build system for the Visual C++ and MinGW builds.

  3. Grayscale bitmaps can now be compressed from/decompressed to using the TurboJPEG API.

  4. jpgtest can now be used to test decompression performance with existing JPEG images.

  5. If the default install prefix (/opt/libjpeg-turbo) is used, then make install now creates /opt/libjpeg-turbo/lib32 and /opt/libjpeg-turbo/lib64 sym links to duplicate the behavior of the binary 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 (can be disabled with configure or CMake options)

  8. Added a TJ_YUV flag to the TurboJPEG API, which causes both the compressor and decompressor to output planar YUV images.

  9. Added an extended version of tjDecompressHeader() to the TurboJPEG API, which allows the caller to determine the type of subsampling used in a JPEG image.

  10. Added further protections against invalid Huffman codes.

1.0.1

Significant changes relative to 1.0.0:

  1. The Huffman decoder will now handle erroneous Huffman codes (for instance, from a corrupt JPEG image.) Previously, these would cause libjpeg-turbo to crash under certain circumstances.

  2. Fixed typo in SIMD dispatch routines that was causing 4:2:2 upsampling to be used instead of 4:2:0 when decompressing JPEG images using SSE2 code.

  3. The configure script will now automatically determine whether the INCOMPLETE_TYPES_BROKEN macro should be defined.

1.0.0

Significant changes relative to 0.0.93:

  1. 2983700: Further FreeBSD build tweaks (no longer necessary to specify --host when configuring on a 64-bit system)

  2. Created symlinks in the Unix/Linux packages so that the TurboJPEG include file can always be found in /opt/libjpeg-turbo/include, the 32-bit static libraries can always be found in /opt/libjpeg-turbo/lib32, and the 64-bit static libraries can always be found in /opt/libjpeg-turbo/lib64.

  3. The Unix/Linux distribution packages now include the libjpeg run-time programs (cjpeg, etc.) and man pages.

  4. Created a 32-bit supplementary package for amd64 Debian systems, which contains just the 32-bit libjpeg-turbo libraries.

  5. Moved the libraries from */lib32 to */lib in the i386 Debian package.

  6. Include distribution package for Cygwin

  7. No longer necessary to specify --without-simd on non-x86 architectures, and unit tests now work on those architectures.

0.0.93

Significant changes since 0.0.91:

  1. 2982659: Fixed x86-64 build on FreeBSD systems

  2. 2988188: Added support for Windows 64-bit systems

0.0.91

Significant changes relative to 0.0.90:

  1. Added documentation to .deb packages

  2. 2968313: Fixed data corruption issues when decompressing large JPEG images and/or using buffered I/O with the libjpeg-turbo decompressor

0.0.90

Initial release