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September 2000
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2000.09.07 05:00 "Re: OJPEG code", by Tom Lane
"Michael O'Rourke" <morourke@Adobe.COM> writes:
> At least of of the current test files for libtiff is YCbCr with OJPEG
> compression. How do I turn on OJPEG support?
There is none, never has been any, and no one that I know of has the
slightest interest in creating OJPEG support. OJPEG is such an unholy
mess that there's no prospect of having any really useful functionality.
See ftp://ftp.uu.net/graphics/jpeg/TIFFTechNote2.txt.gz --- and bear in
mind that the tech note naively assumes that implementors would actually
make some good-faith effort to follow the spec. In the real world,
almost every type-6 TIFF I've ever seen violates the spec in some minor
or major way (and that's only counting the unambiguous aspects of the
spec :-().
The bottom line is that OJPEG is not a standard, it's just a tower of
Babel. Do yourself and your users a favor: stay far away from it.
The OJPEG files in the libtiff test set are just a relic of bygone times.
They should be replaced by new-style TIFF/JPEGs, but since the test set
hasn't been updated in many years, it hasn't happened yet...
regards, tom lane
organizer, Independent JPEG Group