2006.04.14 18:13 "Re: [Tiff] BigTIFF Suggestion", by Joris Van Damme

Antoine,

This is probably a stupid comment...

I thought you could create your own tags with tiff? I would be shocked to find that that wasn't the case with bigTiff (having strictly 0 knowledge of the aforementioned...)... so why not create your own tag and be done with it?

Because a tag's logical scope is the IFD, not the file.

Suppose that wouldn't be the case. Then each IFD unlink, or IFD append, or IFD copy operation or whatever, had to scan through every IFD in the file to find tags that it should change to reflect that operation. Even more importantly, knowledge of all tags would be required for these operations, and thus the whole scheme of private tags would be invalidated.

ps. the tag may not be "standard", but that doesn't stop anyone from optimising their app... after all - what about wang annotations?

Wang annotations like any properly designed private tag that doesn't break TIFF, is a registered private tag with strict IFD scope.

Best regards,

Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
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