2003.08.07 06:11 "[Tiff] Custom tags", by Andrey Kiselev
I've been trying to port some of our old software to use the new CUSTOM tag facility (v3.6.0 beta 2 TIFF source). I am able to read out the custom tags stored in my TIFF images using TIFFGetField() after making a call to TIFFSetTagExtender() to 'configure' my custom tags. The problem I'm having at the moment is that I don't seem able to store modifed versions of the custom tag data to the file. I open the files using the 'r+' mode (i.e. read/write) and grab the directory/tag information. The TIFFGetField() function confirms that I'm reading the custom data correctly. I then use TIFFSetField() to modify the custom tag data and again call TIFFGetField() to confirm that the data has changed (at least in the TIFF data structure). The next thing I do is a TIFFClose(). This appears to close the file handle, but the file has not been updated with the new tag data. I tried doing a 'TIFFRewriteDirectory()' before calling TIFFClose() to try to force the directory update, but this generates a 'segfault', so I assume that I'm not using the CUSTOM tags correctly. I've also tried 'TIFFCheckpointDirectory()' with a similar problem. In both cases, the resultant TIFF file is corrupted and no longer readable by the TIFF library.
Segfault is always an issue for Bugzilla. Could you provide a sample code, demostrating the problem?
Andrey V. Kiselev
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