TIFF and LibTiff Mail List Archive


1998.07.29 19:13 "16 bit grayscale", by Mark Koch
1998.07.29 20:49 "Re: 16 bit grayscale", by Tom Lane
1998.07.29 22:22 "Re: 16 bit grayscale", by Doug Morris
1998.07.29 23:21 "Re: 16 bit grayscale", by Sam Leffler
1998.07.30 16:20 "Re: 16 bit grayscale", by Doug Morris
1998.07.30 16:25 "Re: 16 bit grayscale", by Daniel McCoy
1998.07.30 18:35 "RE: 16 bit grayscale", by Ed Grissom

1998.07.29 20:49 "Re: 16 bit grayscale", by Tom Lane

I'm a bit confused. After reading the TIFF 6.0 spec I was under the impression that TIFF grayscale images were restricted to 4 or 8 bits/sample.

If we had a FAQ this would be in it. An awful lot of people seem to read the "baseline TIFF" subset documentation and think that all TIFFs are constrained by the baseline subset.

Baseline TIFF is not full TIFF. Full TIFF allows at least 1-32 bits/sample, not to mention 4- and 8-byte floating point samples, for all supported colorspaces. (Well, maybe not for palette images.)

Actually I don't even see a restriction to those values in the description of BitsPerSample... but it would be reasonable to assume that you should be able to represent the data range in the MinSampleValue and MaxSampleValue tags, so given the limited set of datatypes available for tags, those are probably the only depths TIFF can be said to support.

Also see section 19 of TIFF 6.0 concerning valid sample data types.

regards, tom lane