2004.12.10 21:52 "Re: [Tiff] Q: writing tiled TIFFs", by Bob Friesenhahn

the problem, it turns out, is that none of the applications i was trying to read the image with handle tiled TIFF correctly. Photoshop can, but not much else.

libtiff itself can read tiled images. TIFFRGBA interface (coded in tif_getimage.c file) shows how to work with tiles. Unfortunately it is not a trivial code, it covers many variants of bit depths, planar configurations, orientations etc. In despite of this it works correctly

The main problem with depending on TIFFRGBA is that one reason for using tiled images is to handle large images. The TIFFRGBA interface requires an enormous amount of memory for large images.

When GraphicsMagick was updated to support reading tiled TIFF on a per-tile level, the read times for a large (1GB) tiled TIFF file improved tremendously.

Bob

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Bob Friesenhahn
bfriesen@simple.dallas.tx.us
http://www.simplesystems.org/users/bfriesen