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July 2007
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2007.07.05 10:06 "Re: BigTIFF extension", by John Aldridge
Joris wrote: > 1) BigTIFF is TIFF. No it's not :-) It's not in the TIFF specification http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf which also claims that TIFF is an Adobe trademark, so presumably they are the people entitled to specify it! However, forget what we call it. I think the following statements are uncontentious a) No BigTIFF file will be readable by any existing TIFF processing code. Many such applications will be in use in the field for many years. Even if the application is updated by the authors, many users will not want to upgrade to the latest version. I still use PaintShop Pro 7, for example, because the improvements in later versions are not worth the upgrade cost to me. b) BigTIFF files will be readable by pretty much any application which is recompiled against an up to date version of libtiff (or presumably pretty much any other TIFF library, I would hope). We have a reasonable expectation, then, that the distinction between the two formats will eventually become insignificant. c) TIFF has always had a problem with applications supporting only a subset of its possible format options. The BigTIFF format is similar to this in many ways, but with the following differences of degree: * The error messages issued by non-supporting applications are less helpful (something like "not a TIFF file", rather than "unsupported compression type"). * BigTIFF support is easier to add to existing applications (it's all in the library) rather than, say, tile support which typically requires application code change. d) The image/tiff MIME Sub-type Registration (RFC 2302) refers explicitly to TIFF6 and "all of the profiles and extensions that build on (it)". Unless IANA amend this to include BigTIFF data, it'll be hard for web servers to set this properly unless the files have a different suffix. So it comes down to a balancing act: is it better to improve the user experience for people with non-BigTIFF supporting applications, or to avoid the possible confusion caused by a separate type suffix when in the long term we hope that the vast majority of applications won't need to distinguish them. I guess it depends on your take on how long "long term" is, and how vast "vast majority"!