I want to access custom TIFF tags

I am interested in reading and writing custom tags in TIFF files using MATLAB. It appears, from a cursory review of the LibTiff website, that invoking tiffmergefieldinfo with a list of the custom tags I need to work with might be enough. But the call is not supported in the tiff object.

I would prefer to not maintain a custom build of the LibTiff library, although that would probably work.

Has anyone worked in this area already?

Answer 1

[Ashish Uthama]

Mark, would the output of imfinfo be of any use? I think it reads custom tags (as 'unknown' tags in the output).

[Mark Delaney]

imfinfo is adequate to read custom tags. I want to update a custom tag with new value and write the tiff to disk. So I need more.

[Ashish Uthama]

Mark, if they are numerical values or have fixed length, you could attempt to use the offset field of the unknown tag to gain raw-access to the location of the value in the file (fopen,fseek, fwrite, fclose). Of course, I am sure you are aware of the risks of doing so :)

[Mark Delaney]

Possible. Painful. Would be very nice to be able to open tiff, do

t_out.setTag(myCustomTagID, 123)

and write t_out to the tiff directory or hte tiff file. The value proposition in MATLAB is all about working at higher levels of abstraction. It is great to have fseek et. al. for when all else fails, but much better to not need it.