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Thread

2000.09.01 16:51 "YCbCr test file(s)?", by Michael O'Rourke
2000.09.06 21:16 "OJPEG code", by Michael O'Rourke
2000.09.07 05:00 "Re: OJPEG code", by Tom Lane
2000.09.07 12:31 "Re: OJPEG code", by Joris Van Damme

2000.09.07 05:00 "Re: OJPEG code", by Tom Lane

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