AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

1996.12.11 02:01 "Confusing TIFF Tags", by Hugues Talbot
1996.12.11 10:17 "Re: Confusing TIFF Tags", by Niles Ritter
1996.12.11 18:31 "Re: Confusing TIFF Tags", by Sam Leffler

1996.12.11 18:31 "Re: Confusing TIFF Tags", by Sam Leffler

I'm confused by (at least) one thing in Sam's library. Some tags, like the SampleFormat tag (#339), which help interpret each data sample in a pixel, should be associated with as many values as there are samples per pixel, according to TIFFv6.0

Yet Sam's library allows to retrieve only one value for this tag per subimage, regardless of the number of samples. The TIFFGetField function should return an array of values, not a single one.

There are other examples, like SMinSampleValue, SMaxSampleValue, etc.

Is this a known libtiff limitation or is this a policy? in any case where can I find some documentation about these puzzling facts?

The library does not support certain tags in their most general form. Examples are the above, Compression, MinSampleValue, MaxSampleValue, and BitsPerSample. SamplesPerPixel is documented in libtiff(3T); I can't recall where the restrictions on the other tags are documented.

If you believe it is important to support per-sample values for any of the tags the library currently restricts then feel free to provide the necessary changes to the library+documentation.

        Sam