2004.04.23 13:12 "Re: [Tiff] Large TIFF files", by Joris Van Damme
Most important is that any file which does not in fact exceed 2GB must be readable by old code.
I think there may be consensus about that, the point has been raised before, but little has been said about how exactly to achieve this.
The library cannot know in advance how large the TIFF to write is going to be, right? In fact, it's quite possible that the library user / application code does not know in advance, even disregarding unpredictable compression factors.
Bob raised the hope that a simple redefinition of some types may allready do the job. I'm not a C man myself, wouldn't know for sure, but does this not exclude 32bit and 64bit TIFF living in the same library? If I'm not mistaking, this is the way LibJpeg supports both 8 and 12 bit jpeg, but one needs two seperate compiled LibJpeg libraries to support 'em both in the same app as a consequence. But I'm not a C man, please point out the errors in my thinking.
Is it then an option to include a boolean 32bit/64bit selector in the main LibTiff TIFF structure instead? Thus allowing applications to select either bitdepth *in advance*, for example by means of a flag of some sorts in the TIFFOpen/TIFFClientOpen call? And rewriting some of the IFD handling code to deal with either case?
Joris Van Damme
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