https://bugs.kde.org/show_bug.cgi?id=454116
amyspark <a...@amyspark.me> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
Latest Commit| |https://invent.kde.org/grap
| |hics/krita/commit/dd4d2b4b7
| |93a42b2c7406dfc63fc108ea890
| |5ec5
--- Comment #1 from amyspark <a...@amyspark.me> ---
Git commit dd4d2b4b793a42b2c7406dfc63fc108ea8905ec5 by L. E. Segovia.
Committed on 28/06/2022 at 16:01.
Pushed by lsegovia into branch 'master'.
tiff: support YCbCr + JPEG imports
This commit enables reading JPEG-compressed TIFFs that use the YCbCr
colour space. This is not possible to do with the standard libtiff API
because of Very Bad Decisions :tm: that were taken in the past, both
during the 6.0 standardization [1] and its implementation [2].
To do so, I've implemented a custom made strip decoder that, when the
combination of COMPRESSION_JPEG and PHOTOMETRIC_YCBCR is detected,
redirects to a (also custom made) buffer stream that performs automatic
interleaving and upsampling of the image planes. This data is shaped
into the form specified in the TIFF 6.0 Specification [3], then fed
to the existing YCbCr readers. The planes are decoded using
libjpeg-turbo (to avoid the mindbending API of libjpeg) into three
separate planes without upsampling.
There's a catch, however. Unlike libjpeg-turbo, libjpeg provides a
direct API to prime the decoder with the coefficient tables that are
provided in TIFFTAG_JPEGTABLES, and which libtiff uses as part of
TIFFjpeg_read_header. To remediate this, I've patched libtiff-turbo to
add a tjReadCoefficientTables API, that takes a reference to the tables
and forwards it to the decoder.
CCMAIL: kimages...@kde.org
[1]: DRAFT TIFF Technical Note #2, 17-Mar-95.
<http://libtiff.maptools.org/TIFFTechNote2.html>
[2]: 2022.06.11 07:23 "Re: [Tiff] How to read JPEG-compressed YCbCr
TIFFs", by Joris Van Damme. <https://www.asmail.be/msg0054881320.html>
[3]: "Ordering of Component Samples". In: TIFF Revision 6.0 Final. June
3, 1992: Adobe Developers Association, pp. 93-94.
M +4 -4 3rdparty/ext_jpeg/CMakeLists.txt
M +14 -0 CMakeLists.txt
A +4 -0 config-jpeg.h.cmake
M +1 -1 plugins/impex/tiff/CMakeLists.txt
M +138 -2 plugins/impex/tiff/kis_buffer_stream.cc
M +57 -1 plugins/impex/tiff/kis_buffer_stream.h
M +177 -6 plugins/impex/tiff/kis_tiff_import.cc
M +1 -0 plugins/impex/tiff/kis_tiff_import.h
D +- -- plugins/impex/tiff/tests/data/quad-jpeg.tif.png
A +- -- plugins/impex/tiff/tests/data/results/quad-jpeg.tif.png
R +- -- plugins/impex/tiff/tests/data/sources/quad-jpeg.tif [from:
plugins/impex/tiff/tests/data/quad-jpeg.tif - 100% similarity]
https://invent.kde.org/graphics/krita/commit/dd4d2b4b793a42b2c7406dfc63fc108ea8905ec5
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