2002.03.05 20:58 "Re: Photoshop Alpha Channel", by Chris Cox
I'm looking for some help with adding a grayscale TIFF to a CMYK tiff as a photoshop alpha channel. I know that Photoshop does not mark these in strictly the correct way. Can any one suggest how I can achieve this?
What do you mean "not mark these in strictly the correct way"? Photoshop writes the transparency channel as type 1 (associated), and additional channels get marked as type 0 (unspecified) because we don't know how the user intends to use them.
Any additional, non-associated channels you put in the TIFF file will be read as alpha channels by Photoshop. Only one associated channel will be read by Photoshop, as transparency.