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June 2004
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2004.06.07 14:05 "Re: Reading from part of a TIFF while writing another", by Frank Warmerdam
James Carroll wrote: > Hello, > > I'm dealing with largish tiff files, (Jpeg compressed, tiled.) and > I'm wondering if it's possible to write to part of a tiff _while_ I'm > reading from other parts. > > One example is writing a second page of a tiff that's a function of > the first page. > Both pages are too big to fit in memory, so I have to be in read and > write mode at the same time. Jim, As long as you are writing to a different directory than you are reading from it *should* be fine to have two file handles on the file, one in read mode and one in update or append mode. However, if you are reading and writing on the same directory this should likely be done with a single file handle in update mode. This is an area of some ... risk. Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent