2006.12.01 22:21 "Re: [Tiff] ITULAB JPEG support", by Joris Van Damme
More and by hell, I don't understand what color process different of YCbCr ( in turn nothing ),
a LibJpeg might apply to ICCLAB or ITULAB...
However, I perfectly agree with something like trashing-out whatever color space conversions
below tif_jpeg entry point, ( note that now, anyone can process color conversion as he want,
and then feed codec with it as YCbCr ) but: elimination of the horrible JPEGCOLORMODE pseudo-tag ( and real abomination )
will not solve ***the*** problem: the demented xxx-subsampling tag, that a not too much brain-damaged libtiff would understand for jpeg files, as a parameter in the in the same sense
that quality factor on the compression side, and override to (1,1) on the decompression side
(in some way as strip_chopping ).
More and by hell, we have a real language problem here. I really don't understand what you're saying.
I've been toying with the idea of adding a small interface on top of TIFFReadEncodedXxx. This small interface should be named TIFFReadSubsampledXxx. It will first call TIFFReadEncodedXxx, and if subsampling is in effect, it will de-subsample the data. It should be a valid call even if no subsampling is in effect, in which case it returns immediatelly after calling TIFFReadEncodedXxx.
This way, people will not have to worry about subsampling if they just remember to call TIFFReadSubsampledXxx where they used to call TIFFReadEncodedXxx. It is in the proper position, i.e. it is independent of the compression or color mode used, works on JPEG compressed YCbCr as well as on flate compressed CIELAB or whatever.
Is this what you are asking after?
Joris Van Damme
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