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June 2011
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2011.06.30 16:02 "Re: Is it possible to read a large tiff image in portions?", by David Burken
Hib, On 06/30/2011 11:21 AM, Hib Eris wrote: > Hi, > > I am trying to handle large tiff files using libtiff, for example, an > image of size 13244 x 18724 pixels. > When I use > int TIFFReadRGBAImage(TIFF *tif, u_long width, u_long height, u_long > *raster, int stopOnError), > then the "raster" must be 13244 x 18724 x 4 = 991922624 bytes. > That is almost 1 GB and that is too much for my computer. > > To avoid this, I would like to read and process the image in pieces, > how should I do this with libtiff? > > I noticed > int TIFFReadRGBATile(TIFF *tif, uint32 x, uint32 y, uint32 *raster), > but that seems to only work for tile-based tiff images. I would like > to have a solution for all tiff images, not only tile-based ones. I'll point you to an example. Ossim is tile based under the hood. So all of our image readers have one purpose, to stuff a tile of image data like 256x256. Since tiff can be many flavors I'd start at ossimTiffTileSource::getTile as it takes multiple paths. http://trac.osgeo.org/ossim/browser/trunk/ossim/src/ossim/imaging/ossimTiffTileSource.cpp Hope that helps. Another option of course would be to link with ossim, open your image and call getTile for the rectangle you want. Hope that helps, Dave > Thanks, > > Hib Eris > _______________________________________________ > Tiff mailing list: Tiff@lists.maptools.org > http://lists.maptools.org/mailman/listinfo/tiff > http://www.remotesensing.org/libtiff/ >