2006.04.04 16:50 "[Tiff] BigTIFF Suggestion", by Larry Michaels

2006.04.05 00:17 "Re: [Tiff] BigTIFF Suggestion", by Joris Van Damme


I appreciate your help. When I referred to a CRC, I meant that I save a CRC of the four-byte offset only. It may be overkill, but it, along with my little signature, allows me to be quite certain that what I read at the end of the file is what I wrote there and nothing else. That way, there is very little danger of seeking to the wrong offset for appending if I read a file written by a different app or one which was truncated.

Consider following scenario:

I do not want to put the information in a separate file because users may move and rename their files.

I can understand that. I honestly fear that may not be a real good solution to your problem.

We have a number of requirements for image sequence file, some of which conflict with each other. The two biggest are the ability to hold very large numbers of very large images, and to be able to be written quickly. Our application does not yet support files larger than 4GB, but I have been told to add the support, so I have been comparing various options, one of which might be BigTIFF. I think that PDF is probably too complicated for our purposes. I may implement a proprietary format optimized for our needs and also allow users to save their files as BigTIFF for compatibility with other applications.

I see... Possibly, a clearly non-TIFF but likely TIFF-based proprietary format may be the best solution, if you're ready to put in that kind of effort. Even if your only modifications aside from appended last-IFD-offset are only by pre-pending some stray bytes (additional signature?) and changing some important ones (TIFF signature?), that'll be sufficient in keeping other apps from interfering with your files, solving your problem but excluding a lot of bad scenario's from happening.

Joris Van Damme
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