2007.02.05 03:28 "[Tiff] Request help On OJPEG Compression In Libtiff", by Steven Lim

2007.02.05 19:14 "RE: [Tiff] Request help On OJPEG Compression In Libtiff", by Chris Cox

That's because most (if not all) of Microsoft's implementations are based on the same buggy library (it has other serious problems).

We have several bugs filed with Microsoft about those problems, and they are supposed to be fixing the code (was scheduled for Vista, but we haven't heard any response on the bugs and I haven't had time to verify in Vista).

And just because Microsoft propagates a bug doesn't mean that you should as well.

Don't write compression code 6 in TIFF.

You can read it, but you should never write it.


-----Original Message-----
From: Joris [mailto:joris.at.lebbeke@skynet.be]
Sent: Mon 2/5/2007 11:08 AM

To: Chris Cox; Steven Lim; tiff@lists.maptools.org

Subject: Re: [Tiff] Request help On OJPEG Compression In Libtiff

  1. REALLY, don't do that -- the old JPEG encoding is rarely supported (I'm sorely tempted to add a more severe note to Photoshop when encountering them to say that the file is buggy and the user needs to complain to the vendor that wrote it).

Hate to spoil your fantasy, but Windows XP and apparently Vista standard previewing of images supports nothing but OJPEG. Same goes for Microsoft Document Imaging stuff, or so I'm told. Another vendor that produces nothing but OJPEG, is Kofax, which apparently is no small fish either.

Apparently, many people have a need to be compatible with these products, in that they need to write files that these products can read fine. Actually, my own customers wanted me to add OJPEG writing support to my own codec for exactly this reason, and after much consideration I had to give in to these needs, as I do understand them even if I very much dislike the situation and the bad original OJPEG specification.

We seem to be trying to dry the kitchen floor, but we forgot to close the water tap first. Perhaps a more severe note in Photoshop could get some people's attention, but then again, I guess it's not very likely the issue didn't get their attention before. People have been screaming about this issue for about two decades now.

Furthermore, the message in Photoshop might look a bit silly, given the fact that Adobe has neglected to update the spec sofar. Any lock-in strategy from an OJPEG vendor, can be backed up by a pointer to the current TIFF specification. We might know there's supplements, but there's no reason why anyone else should know, and the web is full of pointers directly to the TIFF 6.0 spec PDF that bears no indication of the existence of supplements that override it.