2006.10.07 17:43 "Re: [Tiff] OJPEG image - worked OK in 3.7.4, not in 3.8.2", by Joris Van Damme

Chris,

i'm upgrading to libTiff 3.8.2. as part of the upgrade, i run against a set of TIFFs, including pics from the "pics-3.6.1.tar.gz" suite.

it looks like 3.8.2 has trouble with one of those pics, "smallliz.tif" - the color planes are misaligned and skewed.

it reads fine if i swap-in my 3.7.4 version of LibTiff.

        any ideas?

I think you are refering to previous attempt at OJPEG support, as included in the official stable distribution of LibTiff 3.8.2?

There's numerous problems with that one, including stability problems. It may have gotten somewhat worse in the last couple of versions on some images, and somewhat better on some others, but it's essentially flawed.

That's why we've replaced it with a totally new implementation. This is currently in CVS. One difference is that this new implementation doesn't support the JPEGCOLORMODE hack, so you either have to deal with YCbCr subsampling yourself, or use the RGBA interface (I've some third more convinient solution planned, but it's too early to discuss it). But the major difference is that it supports every OJPEG image we've been able to find from many different sources, and, most importantly, it's stable. We plan even plan to enable it by default, in the next LibTiff release.

But, so, the bad news is we can't support the old version that was in there up to version 3.8.2 at this time. If you want OJPEG support in any current official distribution, you're pretty much on your own. And I recommend against even trying, the stuff isn't even stable. If you really need OJPEG, grab CVS instead.

Best regards,

Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
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