2007.07.03 18:06 "Re: [Tiff] Old corrupted TIFF data - "Can not read directory count"", by Bob Friesenhahn

I think I've cracked this. It looks like these were read improperly off CD originally. I re-read the original CDs using Windows rather than Linux (a tremendous moral defeat, that) and got back readable TIFFs that were longer than the originals and for which the directory offsets made sense.

It sounds like the Linux CD filesystem code has a bug.

Can TIFF files be sparse? That is, could the directory have been written at a specific location set by block size, even though the data didn't actually reach that far? That's my best theory so far: that the files were dumped out with file system offsets then read back in sequentially, losing a few hundred (meaningless) bytes in the process.

TIFF files on any filesystem which supports 'holes' could have a hole in them when all the data in a long contiguous region (at least a disk block's worth) is zeros. But it is unlikely that your CD filesystem supports sparse files.

Bob
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Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/