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

2007.07.05 21:38 "Re: [Tiff] Re: Tiff Digest, Vol 38, Issue 12", by Joris Van Damme


Stick with reality. What do programmers/users know about TIFF, what does it stand for? Any part of that actually changed?

Compatibility with all existing software.

We've seen that argument before. I've replied before (amongst other replies) that the same goes for tiling in TIFF, it was not compatible with all existing software either. So far, nobody contradicted my reply, so let's stop returning to square one in this part of the discussion.

With a tiled TIFF or different compression schemes, the file is recognized as TIFF and gets a more useful error message ("unsupported compression scheme", "unrecognized storage method", etc.).

BigTIFF does have the disadvantage over all previous changes in that it will get "Not a TIFF file" or "corrupt file" error messages from all previous software.

With all due respect, but, that too has been said before. The answer that has been given, wich you may or may not feel is sufficient, is that to the end user getting "Cannot open TIFF because Strip tags are missing", or "Cannot open file because not a TIFF file", or the old-time favorite of old Photoshop versions "Cannot open file because failed to open file", does not make a really significant difference. The end result is still, cannot open file. End users are furthermore mostly not aware of what are strip tags, or anything, and to them the old-time favorite "Cannot open file because failed to open file" makes most sense of all.

Of course, having Photoshop and its users in mind, you think of meaningfull errors and power users. That's not a very representative situation, though. And still, cannot open file, is cannot open file, is tough luck to power users and newbies alike. So in short, I think we all agree there is some difference in stage of failure and error message between the incompatibility caused by coming of tiling and the incompatibility caused by the coming of BigTIFF, but some of us argue the difference is totally academic and completely negligable to Joe User.

Feel free to dissagree, but please don't loose track of other important considerations. Photoshop, like most of today's GUI apps, allows selection of file format when saving a file, followed by an option dialog specific to the file format. Are you inclined to feel good about having users select between ClassicTIFF and BigTIFF in the first step, to present a different same clone of the same option dialog depending on that choice? Or do you feel it more natural to allow just selection of 'TIFF' as file format in the first step, to next present to the user the choice between ClassicTIFF and BigTIFF in the TIFF options dialog? Doesn't the latter sit better? If so, I'm inclined to think the reason it sits better is that it's closer to the truth: ClassicTIFF and BigTIFF are different version of the same format. Next, consider that the latter is only possible if ClassicTIFF and BigTIFF share the same extension, as extension is selected in the first file format selection step.

Another important consideration is that we may implement on-the-fly automatically rewriting of ClassicTIFF as BigTIFF during creation process if the file hits ClassicTIFF's size limit. Note that this, too, is logically only possible if both versions share the same extension.

Whatever you may feel about all other considerations, that I do feel strongly about, the latter two are two of the ones that leave little room for discussion.

Best regards,

Joris Van Damme
Download your free TIFF tag viewer for windows here: