AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

2000.04.18 15:21 "Problem with IL private TIFF tags", by Ariel Ben-Porath

This is related to TIFF in SGI's ImageVision Library, not to the TIFF library, I hope it is not considered rude to post here (to my justification, I can tell you I am desperate...)

Can anyone shed some light on writing private TIFF tags with IL:

I am using SGI's ImageVisionLibrary (il and ifl calls) to write a TIFF file. I would like to add a private TIFF tag, and before calling up Adobe and asking for a tag to be allocated, I experimented with the SetItem() and SetTag() methods, and it seems that they would only accept publicly known tags. Moreover, when I try to write a tag whose ID is above 64000, a range which is defined by the TIFF 6.0 standard as free usage (i.e. tags can be used and re-used, there is no registration of tags in this range), I still get the "Unknown Tag" error message.

I need a tag that would be of type BYTE (TIFFTAG_BYTE), and of length greater then 1. The syntax I am using is:

 SetItem(iMyTIFFfag, TIFFTAG_BYTE, iMyTagLength, &MyTagData);

Am I doing this the wrong way, or is the library really limited only to publicly known tags? Anyone with a sample of code that actually writes a private tag which is some array of bytes?

Many thanks,
Ariel.