2005.12.02 19:03 "[Tiff] Odd offsets in IFD entries", by Gary McGath

2005.12.03 23:53 "Re: [Tiff] Odd offsets in IFD entries", by Joris Van Damme

In TIFF, are all offsets specified by an IFD entry required to be on an even byte boundary?

Yes, absolutely.

But we've encountered large numbers of files that violate this requirement and still work with existing software.

In TIFF, strict validation with binary result is mostly useless. This word alignment of data blocks is just one of the rules that are often violated, but don't really matter much to most readers. A full diagnostic is more feasable, less arbitrarilly, and more usefull. It allows you to state the exact violation(s), the severity and impact on mainstream readers, etc.

A TIFF with floating point image date, or with a 3bits per pixel palette, may be perfectly legit, but nevertheless not supported by most mainstream readers. A full diagnostic output of a validator allows you to include comments on portability in these cases.

Joris Van Damme
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