2002.03.22 17:07 "Re: TIFF image tiles from the UK Ordnance Survey Errors out.", by Jason Summers

I am trying to load a TIFF image tiles from the UK Ordnance Survey. It errors out with a variety of warnings, the most critical of which seems to be:

Incorrect count for field "RowsPerStrip" (0, expecting 1); tag ignored

I think this is the only significant problem. RowsPerStrip value #1 is 2000, which is correct, but the count indicates there are zero values, so libtiff (rightly) ignores it. In the absence of a valid RowsPerStrip tag, it probably assumes that the entire image is in a single strip (which it is not).

And

Incorrect count for field "StripOffsets"(2000, expecting 1); tag ignored

The StripOffsets tag looks okay. This error is a consequence of not knowing the correct RowsPerSTrip.

Probably, changing the byte at offset 110 (0x6e) from 0 to 1 will make the file usable. Or maybe you could hack libtiff to think that a count of 0 means 1.

They charge a fee for these files,

Then you have reason to be upset with them for selling bogus TIFF files.

Jason Summers