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March 2008

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2008.03.27 17:43 "Open Tiff File in Read and write mode.", by Jean-michel Frecinat

2008.04.02 10:29 "Re: Open Tiff File in Read and write mode.", by Gerben Vos

2008.04.02 10:29 "Re: Open Tiff File in Read and write mode.", by Gerben Vos

Jean-Michel FRECINAT wrote:

> I use libtiff 3.8.2 and i have some problems with memory. When I
> create a 30000x10000 pixels in cmyk, i have to have a lot of RAM
> memory (about 2-3GB).

> But my problem, i would open my file in read and write mode to edit
> and to process some pixels and after save the scanline into file.

I'm not very familiar with opening TIFFs in read-and-write mode, but
in general this is only going to work well if the TIFF is uncompressed.
Otherwise, the sizes of the new tiles/strips will differ from the old
ones, and libtiff will append the new data to the end of the TIFF,
leaving a large gap of unused data. (The TIFF is not one single large
strip, I hope.)

Also, maybe processing the TIFF by tile or strip works better than by
scanline.

					Gerben Vos.

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