TIFF and LibTiff Mail List Archive

1998.07.21 14:18 "Re: Tiff2ps with JPEG", by Tom Lane

> I am attempting to use the tiff2ps utility in UNIX for TIFF images
> stored with JPEG compression. The TIFF images are scanned using a
> variety of scanners and drivers. I am getting an error message when I
> try to create the postscript file - 'Old-Style JPEG compression
> support is not configured'.

I'm afraid you're out of luck. Libtiff only supports TIFF/JPEG per the new Compression=7 style defined in TIFF Tech Note #2. Evidently some of your source files use one or another interpretation of the old Compression=6 style.

Compression=6 is a real morass, not only because of the old spec's ambiguities (which are described in the Tech Note), but because several purported TIFF/JPEG writers write files that are compatible with *no* defensible reading of the old spec. To read their files you have to ignore the specification and instead "just know" where to pull out the data and what it means.

A generic reader that would handle everything that claims to be old-style TIFF/JPEG may not even be possible. It certainly wouldn't be easy, and I would not expect it to work with any variant it hadn't been specifically tested and debugged with. None of the principal libtiff contributors are interested in venturing into that morass.

If you just have one or two sources to deal with, you could decipher the idiosyncracies of their particular interpretations of TIFF/JPEG and then write some sort of conversion program to reformat the data as new-style TIFF/JPEG. See TIFF 6.0 Section 22 and Tech Note #2 for details (they're available at among other places).

I think a couple of people on this list have had to do something like this already... but of course their solutions are no more general- purpose than I'm suggesting yours be.

                        regards, tom lane
                        organizer, Independent JPEG Group