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TIFF and LibTiff Mail List Archive

Thread

1994.01.27 16:11 "JPEG support", by Dwight Kelly
1994.01.27 11:55 "Re: JPEG support", by Niles Ritter
1994.01.28 07:04 "Re: TIFF/JPEG support", by Tom Lane

1994.01.28 07:04 "Re: TIFF/JPEG support", by Tom Lane

Like everyone else, I'm waiting for the next, internally consistent, set of TIFF-JPEG specs to be settled on and published. The end is not yet apparently in sight (Any news, Tom?)

The tiffjpeg group has been sort of on hold since Christmas break. I need to start pushing that again...

We have pretty much agreed to scrap the TIFF 6.0 Section 22 entirely, and devise a new spec that will store fully legal JPEG datastreams in each strip or tile. There are some fine points yet to be cleared up, but in the main I think that is agreed. There will be a new Compression tag value for this design, and the old one will be relegated to the scrapheap of history.

The biggest remaining problem seems to be colorspace representation. TIFF has extensive machinery for describing the colorspace of the data (which is good because raw JPEG has none). But the TIFF spec doesn't address the possibility that the colorspace stored in the file is not the same as the "external" colorspace that the data user wants to deal with. One faction wants to assume that RGB=>YCC colorspace conversion is strictly internal to the JPEG codec and the TIFF tags should describe the original RGB colorspace. Another faction says that's all wrong, the tags should state what's stored in the file. I suspect we may end up storing two sets of colorspace data :-(.

                        regards, tom lane
                        organizer, Independent JPEG Group

PS: Despite what Niles suggested, the tiffjpeg mail list is NOT open to the public at this point; the listserver will not accept subscription requests. If you've got specific expertise with TIFF and are willing to help slog through a lot of nitty details, then send me mail and I will be pleased to add you to the list.