Thursday, July 10, 2008
Update on BigTIFF
Aware Systems' BigTIFF page has just had a significant update. Previously it had strong warnings that the design was still in flux. It now states:
Whilst BigTIFF is not yet an actual official standard, there were quite a few people involved with developing the BigTIFF draft specification, including people from Adobe, and there have been no changes since that time. There are at least two independent implementations (our own AWare Systems AsTiff, and LibTiff since version 4.0). Furthermore, BigTIFF is a small and quite natural progression from TIFF. It seems highly unlikely that an organization with some apparent position of authority (i.e. a standards organization or Adobe) will produce a document on their own that contradicts this draft specification at this stage. We thus feel we can safely recommend adoption of BigTIFF now.
This seems to be more a matter of finally declaring it done (after nudging by me and several other people on the TIFF list) rather than any flurry of recent activity.
The formal description of BigTIFF -- to the extent we can call it "formal" -- is found here. Some issues, notably what MIME type to use, are still open.
There has been talk on the TIFF discussion list of sticking with "image/tiff". However, doing that would contradict IETF RFC 3302, which defines the type in terms of TIFF 6.0. The changes to BigTIFF from TIFF 6.0 are minor in a certain sense, but no TIFF reader following the TIFF 6.0 definition will accept a BigTIFF file. Registering "image/tiff-big" would require publication of a formal standard, and that isn't likely to happen. My own suggestion is informally adopting "image/x-tiff-big".
Anyway, congratulations to all those who have brought BigTIFF to this stage!
Related link: LibTIFF. Beware of imitations such as www dot libtiff dot org!
Since the group behind it is small, and Adobe still stands behind TIFF (though it hasn't done anything new with it in years), I'm sure BigTIFF won't drive TIFF 6.0 out of existence. It will be a niche format for really huge images.
If it actually is implemented as described (which as you say is almost guaranteed) all TIFF files will implicitly be BigTIFF files. The libtiff library is almost certain to add support for BigTIFF almost immediately. Etc.
And in industries like remote sensing, biomedical imaging, and mapping we're already dealing with images in the GB range. Once the ability to store Big(Geo)TIFFs is available, I think you're going to see rather a lot them.
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