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January 1994

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1994.01.27 16:11 "JPEG support", by Dwight Kelly
1994.01.27 18:55 "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.