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May 2004
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2004.05.20 05:35 "Extra samples handling", by <mayankg@iiitb.ac.in>
Hi, Please confirm if i am correct with the extra samples handling in TIFF images. If TIFFTAG_EXTRASAMPLES has: Type as 1(associated alpha): then the color values have to be taken as it is. also the number of extra channels will always be one only. Type as 2(unassociated alpha): then all the color values have to be multiplied by the alpha channel value. Question 1: Are multiple unassociated alpha channels possible? If yes, then how are the final color values calculated? Type as 0(unspecified data): then the extra channels have to be simply ignored. Question 2: Are combinations of Type 2 and Type 0 possible for a particular TIFF image? If yes, do we need to ignore the alpha channel/multilply the color values with the vaues of the color channel accordingly? Thanks, Mayank