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February 2001
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2001.02.21 18:05 "PhotoShop alpha channels and LibTiff", by Chris Losinger
i have a TIFF created in PhotoShop (vers??). it is saved with an alpha channel. when i go to read this image using TIFFReadRGBAImage, the alpha channel is not read. LibTiff treats it as an RGB image, not an RGBA. tracing the code, i found that the alpha channel is marked: EXTRASAMPLE_UNSPECIFIED. when i forced that flag to EXTRASAMPLE_ASSOCALPHA, LibTiff returns the proper alpha channel. what to do about this? is it a photoshop bug or a libtiff bug? -c