2007.07.03 18:37 "[Tiff] BigTIFF extension?", by Phil Harvey

2007.07.05 13:23 "[Tiff] Re: Tiff Digest, Vol 38, Issue 12", by Gary McGath

  1. BigTIFF is TIFF.

No it's not :-) It's not in the TIFF specification


which also claims that TIFF is an Adobe trademark, so presumably they are the people entitled to specify it!

There's a bit of revisionism in the BigTIFF description. The proposal on awaresystems.be refers to the value at offset 2 as a "Version number," which is 42 for "classic TIFF" and 43 for BigTIFF. Yet the TIFF 6.0 specification says that at bytes 2-3 the value is 42, which is "An arbitrary but carefully chosen number (42) that further identifies the file as a TIFF file." This is NOT a version number. TIFF is annoying in that there is no version number specification; you can tell what version was used to write a TIFF file only by what features are used. But putting the number 43 at offset 2 is a statement that the file is not any version of TIFF.

Since BigTIFF diverges from the specification to distinguish itself from TIFF, it should be considered not a version of TIFF, but as a different file format (albeit one derived from TIFF).

Gary McGath
Digital Library Software Engineer
Harvard University Library Office for Information Systems