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November 2010
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2010.11.16 20:09 "Re: unknown field with tag 317 (0x13d) encountered.", by E Rosten
On Tue, 16 Nov 2010, Bob Friesenhahn wrote: > On Tue, 16 Nov 2010, E. Rosten wrote: >> I'm trying to read a TIFF file, which seems to have the predictor set. I >> get the error message: >> >> TIFFReadDirectory: Warning, std::istream: unknown field with tag 317 >> (0x13d) encountered. >> >> and the TIFF appears to be quantized to a very small number of levels. >> This is from my own software and I get very similar results from other >> software installed on the system. I have tried the latest version (3.9.4), >> with the following results from the configure script: > > This file seems to use 16-bits per sample. Perhaps the "quantization" you > are seeing is due to 16-bits being squashed down to 8-bits/sample as > supported by common image display software. Sometimes 16-bit/sample images > only use levels which don't map well to 8-bit. This is a common problem. Ah! Thanks. I've found the bug. It appears that this TIFF doesn't have samplesperpixel set, and I wasn't defaulting it properly to 1. So, I was calling the cooked RGB interface because I didn't know how to cope with 0 samples per pixel. I guess the unknown tag was a red herring. Thanks!x -Ed -- Edward Rosten Machine Intelligence Laboratory http://mi.eng.cam.ac.uk/~er258 Department of Engineering +44 1223 7 65960 University of Cambridge