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TIFF and LibTiff Mail List Archive

Thread

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 11:14 "On 16 bit TIFF palette", by Ivo

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.

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

Ivo