2006.09.15 12:38 "[Tiff] is there alpha component present in Grayscale or Palette color image", by Anurag Singh

2006.09.18 14:39 "Re: [Tiff] is there alpha component present in GrayscaleorPalettecolorimage", by Gerben Vos

TIFF does support unassociated (simple) alpha but the TIFF specification does not define how it should be applied to the image to obtain a viewable result.

Thanks, I thought TIFF only did associated alpha, but your answer prompted me to re-read the description of the ExtraSamples tag and find out how to specify unassociated alpha. Not that I need it anytime soon, but it's good to know. :-)