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February 2007
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2007.02.05 19:29 "Re: Request help On OJPEG Compression In Libtiff", by Joris Van Damme
Chris, Chris Cox wrote: > That's because most (if not all) of Microsoft's implementations are > based on the same buggy library (it has other serious problems). I've indications that this is not the case. The newer Microsoft products don't seem to read the very ugly OJPEG flavours that the early KODAK-WANG code base wrote. Furthermore, that early code base didn't read the cleanest and least bad flavour that my codec currently (reluctantly) writes, and the newer Microsoft code does read that fine. > 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. That's what I told my main codec customer. But he feels he has to make a living, and his customers are demanding that his image library can write JPEG compressed TIFFs that can be read back in Microsoft Document Imaging products. And I have to make a living too, and thus I have to serve his needs. (And I do understand his predicament, BTW.) I did experiment to find the cleanest possible version that Microsoft malware can read, and I found that to be a single-strip OJPEG with one totally valid JPEG stream in the single strip, no additional table markers, and the Strip offset and bytecount reflected in the JpegInterchangFormat and JpegInterchangeFormatLength tags. So this is at least the least filthy version imaginable. Really, Microsoft is causing a whole food chain of vendors to follow in their OJPEG footsteps. Nothing much I can do about that other then starve myself to nobody's gain. I need to be in that food chain. I guess my point is, if you find you have some energy you can devote to dealing with this issue, then marking the TIFF 6.0 document OJPEG chapter as overriden inside that PDF on the one hand, and pushing all your contacts in Microsoft on the other hand, I think could be much more effective then any other action, as that directly deals with both causes for the persistence of this problem. > Don't write compression code 6 in TIFF. > You can read it, but you should never write it. I would like nothing better then to follow your advice. It is my own original point of view. But then there's the reality out there... Best regards, Joris Van Damme info@awaresystems.be http://www.awaresystems.be/ Download your free TIFF tag viewer for windows here: http://www.awaresystems.be/imaging/tiff/astifftagviewer.html