- Clarify that lossless JPEG is slower than and doesn't compress as well
as lossy JPEG. (That should be obvious, because "lossy" literally
means that data is thrown away.)
- Re-generate TurboJPEG C API documentation using Doxygen 1.9.8.
- Clarify that setting the data_precision field in jpeg_compress_struct
to 16 requires lossless mode.
- Explain what the predictor selection value actually does. (Refer to
Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994, Section
H.1.2.1.)
This corresponds to max_memory_to_use in the jpeg_memory_mgr struct in
the libjpeg API, except that the TurboJPEG parameter is specified in
megabytes. Because this is 2023 and computers with less than 1 MB of
memory are not a thing (at least not within the scope of libjpeg-turbo
support), it isn't useful to allow a limit less than 1 MB to be
specified. Furthermore, because TurboJPEG parameters are signed
integers, if we allowed the memory limit to be specified in bytes, then
it would be impossible to specify a limit larger than 2 GB on 64-bit
machines. Because max_memory_to_use is a long signed integer,
effectively we can specify a limit of up to 2 petabytes on 64-bit
machines if the TurboJPEG parameter is specified in megabytes. (2 PB
should be enough for anybody, right?)
This commit also bumps the TurboJPEG API version to 3.0.1. Since the
TurboJPEG API version no longer tracks the libjpeg-turbo version, it
makes sense to increment the API revision number when adding constants,
to increment the minor version number when adding functions, and to
increment the major version number for a complete overhaul.
This commit also removes the vestigial TJ_NUMPARAM macro, which was
never defined because it proved unnecessary.
Partially implements #735
(ChangeLog update forthcoming)
- Prefix all function names with "tj3" and remove version suffixes from
function names. (Future API overhauls will increment the prefix to
"tj4", etc., thus retaining backward API/ABI compatibility without
versioning each individual function.)
- Replace stateless boolean flags (including TJ*FLAG_ARITHMETIC and
TJ*FLAG_LOSSLESS, which were never released) with stateful integer
parameters, the value of which persists between function calls.
* Use parameters for the JPEG quality and subsampling as well, in
order to eliminate the awkwardness of specifying function arguments
that weren't relevant for lossless compression.
* tj3DecompressHeader() now stores all relevant information about the
JPEG image, including the width, height, subsampling type, entropy
coding type, etc. in parameters rather than returning that
information in its arguments.
* TJ*FLAG_LIMITSCANS has been reimplemented as an integer parameter
(TJ*PARAM_SCANLIMIT) that allows the number of scans to be
specified.
- Use the const keyword for all pointer arguments to unmodified
buffers, as well as for both dimensions of 2D pointers. Addresses
#395.
- Use size_t rather than unsigned long to represent buffer sizes, since
unsigned long is a 32-bit type on Windows. Addresses #24.
- Return 0 from all buffer size functions if an error occurs, rather
than awkwardly trying to return -1 in an unsigned data type.
- Implement 12-bit and 16-bit data precision using dedicated
compression, decompression, and image I/O functions/methods.
* Suffix the names of all data-precision-specific functions with 8,
12, or 16.
* Because the YUV functions are intended to be used for video, they
are currently only implemented with 8-bit data precision, but they
can be expanded to 12-bit data precision in the future, if
necessary.
* Extend TJUnitTest and TJBench to test 12-bit and 16-bit data
precision, using a new -precision option.
* Add appropriate regression tests for all of the above to the 'test'
target.
* Extend tjbenchtest to test 12-bit and 16-bit data precision, and
add separate 'tjtest12' and 'tjtest16' targets.
* BufferedImage I/O in the Java API is currently limited to 8-bit
data precision, since the BufferedImage class does not
straightforwardly support higher data precisions.
* Extend the PPM reader to convert 12-bit and 16-bit PBMPLUS files
to grayscale or CMYK pixels, as it already does for 8-bit files.
- Properly accommodate lossless JPEG using dedicated parameters
(TJ*PARAM_LOSSLESS, TJ*PARAM_LOSSLESSPSV, and TJ*PARAM_LOSSLESSPT),
rather than using a flag and awkwardly repurposing the JPEG quality.
Update TJBench to properly reflect whether a JPEG image is lossless.
- Re-organize the TJBench usage screen.
- Update the Java docs using Java 11, to improve the formatting and
eliminate HTML frames.
- Use the accurate integer DCT algorithm by default for both
compression and decompression, since the "fast" algorithm is a legacy
feature, it does not pass the ISO compliance tests, and it is not
actually faster on modern x86 CPUs.
* Remove the -accuratedct option from TJBench and TJExample.
- Re-implement the 'tjtest' target using a CMake script that enables
the appropriate tests, depending on the data precision and whether or
not the Java API is part of the build.
- Consolidate the C and Java versions of tjbenchtest into one script.
- Consolidate the C and Java versions of tjexampletest into one script.
- Combine all initialization functions into a single function
(tj3Init()) that accepts an integer parameter specifying the
subsystems to initialize.
- Enable decompression scaling explicitly, using a new function/method
(tj3SetScalingFactor()/TJDecompressor.setScalingFactor()), rather
than implicitly using awkward "desired width"/"desired height"
parameters.
- Introduce a new macro/constant (TJUNSCALED/TJ.UNSCALED) that maps to
a scaling factor of 1/1.
- Implement partial image decompression, using a new function/method
(tj3SetCroppingRegion()/TJDecompressor.setCroppingRegion()) and
TJBench option (-crop). Extend tjbenchtest to test the new feature.
Addresses #1.
- Allow the JPEG colorspace to be specified explicitly when
compressing, using a new parameter (TJ*PARAM_COLORSPACE). This
allows JPEG images with the RGB and CMYK colorspaces to be created.
- Remove the error/difference image feature from TJBench. Identical
images to the ones that TJBench created can be generated using
ImageMagick with
'magick composite <original_image> <output_image> -compose difference <diff_image>'
- Handle JPEG images with unknown subsampling types. TJ*PARAM_SUBSAMP
is set to TJ*SAMP_UNKNOWN (== -1) for such images, but they can still
be decompressed fully into packed-pixel images or losslessly
transformed (with the exception of lossless cropping.) They cannot
be partially decompressed or decompressed into planar YUV images.
Note also that TJBench, due to its lack of support for imperfect
transforms, requires that the subsampling type be known when
rotating, flipping, or transversely transposing an image. Addresses
#436
- The Java version of TJBench now has identical functionality to the C
version. This was accomplished by (somewhat hackishly) calling the
TurboJPEG C image I/O functions through JNI and copying the pixels
between the C heap and the Java heap.
- Add parameters (TJ*PARAM_RESTARTROWS and TJ*PARAM_RESTARTBLOCKS) and
a TJBench option (-restart) to allow the restart marker interval to
be specified when compressing. Eliminate the undocumented TJ_RESTART
environment variable.
- Add a parameter (TJ*PARAM_OPTIMIZE), a transform option
(TJ*OPT_OPTIMIZE), and a TJBench option (-optimize) to allow
optimized baseline Huffman coding to be specified when compressing.
Eliminate the undocumented TJ_OPTIMIZE environment variable.
- Add parameters (TJ*PARAM_XDENSITY, TJ*PARAM_DENSITY, and
TJ*DENSITYUNITS) to allow the pixel density to be specified when
compressing or saving a Windows BMP image and to be queried when
decompressing or loading a Windows BMP image. Addresses #77.
- Refactor the fuzz targets to use the new API.
* Extend decompression coverage to 12-bit and 16-bit data precision.
* Replace the awkward cjpeg12 and cjpeg16 targets with proper
TurboJPEG-based compress12, compress12-lossless, and
compress16-lossless targets
- Fix innocuous UBSan warnings uncovered by the new fuzzers.
- Implement previous versions of the TurboJPEG API by wrapping the new
functions (tested by running the 2.1.x versions of TJBench, via
tjbenchtest, and TJUnitTest against the new implementation.)
* Remove all JNI functions for deprecated Java methods and implement
the deprecated methods using pure Java wrappers. It should be
understood that backward API compatibility in Java applies only to
the Java classes and that one cannot mix and match a JAR file from
one version of libjpeg-turbo with a JNI library from another
version.
- tj3Destroy() now silently accepts a NULL handle.
- tj3Alloc() and tj3Free() now return/accept void pointers, as malloc()
and free() do.
- The image I/O functions now accept a TurboJPEG instance handle, which
is used to transmit/receive parameters and to receive error
information.
Closes#517
Add a new TurboJPEG C API function (tjDecompressHeader4()) and Java API
method (TJDecompressor.getFlags()) that return the bitwise OR of any
flags that are relevant to the JPEG image being decompressed (currently
TJFLAG_PROGRESSIVE, TJFLAG_ARITHMETIC, TJFLAG_LOSSLESS, and their Java
equivalents.) This allows a calling program to determine whether the
image being decompressed is a lossless JPEG image, which means that the
decompression scaling feature will not be available and that a
full-sized destination buffer should be allocated.
More specifically, this fixes a buffer overrun in TJBench, TJExample,
and the decompress* fuzz targets that occurred when attempting (in vain)
to decompress a lossless JPEG image with decompression scaling enabled.
Introduce a new C API function (tjGetErrorStr2()) that can be used to
retrieve compression/decompression/transform error messages in a
thread-safe (i.e. instance-specific) manner. Retrieving error messages
from global functions is still thread-unsafe.
Addresses a concern expressed in #151.
The changes relative to 1.4.x are only cosmetic (using const pointers)
and should not affect API/ABI compatibility, but our practice is to
synchronize the API revision with the most recent release that provides
user-visible changes to the API.
