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TIFF and LibTiff Mail List Archive

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2000.03.30 11:14 "On 16 bit TIFF palette", by Ivo
2000.03.30 11:37 "Re: On 16 bit TIFF palette", by Peter Nielsen
2000.03.30 17:38 "Re: On 16 bit TIFF palette", by Phillip Crews

2000.03.30 11:37 "Re: On 16 bit TIFF palette", by Peter Nielsen

I have just seen that Wang Imaging and ACDSee do not handle properly TIFF palettes when all r,g,b values are less than 256. As we know, TIFF palette is saved by using uint16 entries, but reader is responsible to check whether the entries are 0-256 or really 0-64K (in which case their values are "expected" to be divided by 256). Apparently, they always shift them 8 bits to the right, and thus they get a completely black palette. Photoshop, of course, does it correct.

PMView also does this correctly. For those of you who don't know PMView: It's a versatile Shareware image viewer & converter. It has been available on OS/2 since 1992 and is now available on Windows as well. Linux and BeOS versions are in the works. Feel free to download it from www.pmview.com

Rule of thumb: When saving the TIFF palette image, always save the r,g,b values (<256) as shifted 8 bits to the left.

Exactly! This is the way it should be done according to the TIFF specs.

Best regards,
Peter Nielsen