2007.07.03 18:37 "[Tiff] BigTIFF extension?", by Phil Harvey
Thread
2007.07.05 13:56 "Re: [Tiff] Re: Tiff Digest, Vol 38, Issue 12", by Joris Van Damme
Gary, John,
- BigTIFF is TIFF.
No it's not :-) It's not in the TIFF specification
http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf
By that token, any new extension of a file format is a different file format, since it is not covered in the previous specification, since it is a new extension. That's ridiculous. We know TIFF for its tags, specific tags, free combination of encoding properties, multi-page support in IFD tree structure, extra sample support, different sampleformats, private data through private tags, etc. None of that changed in BigTIFF. Much attention went to keeping all binary structures as same as possible. BigTIFF is TIFF. It's not covered in TIFF 6.0, because it's new, well, hey, OF COURSE!
Stick with reality. What do programmers/users know about TIFF, what does it stand for? Any part of that actually changed?
If you want to play it really official, and want to ignore the de facto reality, you'll have to wait before you decide if BigTIFF is TIFF, because it's not clear at this point of the specification owner will integrate BigTIFF or not.
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.
You may regard that part of the minimal change that is BigTIFF, that is the new version of the old TIFF, if you wish.
Best regards,
Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
Download your free TIFF tag viewer for windows here:
http://www.awaresystems.be/imaging/tiff/astifftagviewer.html