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May 1994
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1994.05.27 20:49 "Re: handling a strip size that's too big", by Dan Mccoy
>Is there a way to make the TIFF 3.0 (or TIFF 3.3 beta 002) library >read scanline-sized amounts of data instead of strip-size amounts of data? >The reason I ask is that our scanner produces 40MB TIFF files consisting >of a single strip. I would like to read the image a scanline (a few KB) >at a time. However, since the file consists of just 1 strip, when I call >TIFFReadScanline, the TIFF library apparently creates an internal buffer for >the entire 40MB strip, which is causing a performance problem. The library is not currently set up read smaller than a strip. Does the scanner produce compressed or uncompressed files? For uncompressed files, there is a workaround. If you define "STRIPCHOP_SUPPORT" the library (3.3 beta) will fudge files with a single uncompressed strip to make them look like they are composed of smaller strips within the TIFF spec recommendations. Look in tiffconf.h to define it. Look in tif_dirread.c for the code. For compressed data, it can't seek around inside the strips. So reading compressed data in smaller chunks would take a structural change to the library. I hope that helps. Dan McCoy Pixar mccoy@pixar.com