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April 2004
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2004.04.26 09:58 "Re: Large TIFF files", by Joris Van Damme
Rob wrote: > It goes through all tags and replaces all 64 bit tags with 32 > bit tags leaving all data on the same position. I think in general, we have a tendency to loose track of some things I think are defenetely a requirement, nonetheless - cleanness - as much 'streamabillity' as possible (current library goes back only to write offset to next ifd) - total relocatability (defenite requirement) Just my two cents: I don't like the idea of going back and rewriting all IFD. - Remember that it may be a 3 gig file with thousand IFD's - it's not at all 'streamable', data isn't 'partly finished' at any stage - it's not my idea of clean > [fileformat and library are closely related but two different things] Depends. If there is a complete and independent specification, then, yes, there is a fileformat that is not defined by the library. I vote for feasability instead: changing minor things to LibTiff, so that count/offsets can be 64bit. Adobe may be bothering to write a spec, which is a good thing, but I don't think this list is going to be bothered by that. So it is defenetly possible that the new fileformat is defined by library only. > It is not possible to select allways in advance the right mode, as a > user can > decide to enlarge a bitmap to > 4GB. When 32 bit mode was chosen and > there is > a sudden runtime switch to 64bit mode I can imagine quite some > difficulties. > => So the library must work internally in 64 bit mode. The premis, I agree with, but my conclusion is => so the library user must specify if it wants to write a 32bit or 64bit file in advance, using a flag in the primary TIFFOpen call. Joris Van Damme info@awaresystems.be http://www.awaresystems.be Download your free TIFF tag viewer for windows here: http://www.awaresystems.be/imaging/tiff/astifftagviewer.html