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

2007.07.05 20:30 "[Tiff] Re: BigTIFF", by Gary McGath

I believe the BigTIFF spec says something to the effect that if the writing application determines that it will not be generating a >4GB file that it should write ClassicTIFF instead. Therefore, "BigTIFF" is 100% compatible with all existing software up to 4GB. The writing application will normally know all of the parameters before-hand to make this decision.

BigTIFF is also 100% compatible with all existing software for ClassicTIFF images above 4GB. (Since there is no such thing.)

So there you have it -- 100% compatibility.

Then is a file with a BigTIFF header which is less than 4 gigabytes in size in violation of the spec? If so, the sample files at (http://www.awaresystems.be/imaging/tiff/bigtiff.html#samples) are all illegal.

This would be quite an ugly design decision, requiring all writing applications to determine output file size in advance, before they can write anything. For that matter, is there actually a "specification," as opposed to a proposal, yet?

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