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December 2009
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2009.12.10 19:19 "Re: YCbCr", by Joris Van Damme
Steve, > What should I expect to be get from a call to TIFFReadScanline when the > TIFFTAG_PHOTOMETRIC tag is PHOTOMETRIC_YCBCR? It appears that we're > getting rgb, but in the wrong channel order (should be rgb, but is bgr or > vise versa). I only have one test document that is supposed to be solid > red. It's coming out blue. I don't know how the file was made or how to > make another one, otherwise I'd use a file with more colors so I knew for > sure what was going on. Are you using the JPEG_COLORMODE pseudo-tag? It may also be related to a define in LibJpeg, that specifies the channel order of RGB. It may be that in your own copy of LibJpeg, that define is tuned, whilst LibTiff does not expect that. I don't remember from the top of my head the name of the define, but it should be straightforward to find it in a LibJpeg config file. Best regards, Joris