2004.05.20 11:05 "[Tiff] Extra samples handling", by
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?