2004.01.23 20:52 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Chris Cox
On Fri, 23 Jan 2004, Chris Cox wrote:
> >I am by no means an authority on the TIFF specification. My interpretation
> >of the file in question is that a sensible application should render the > >first band in greyscale and ignore the 2nd and 3rd since they are
> >extra samples
> >with no meaning attached.
> Or load the 2nd and 3rd channels as alpha (not transparency) channels
> -- as Photoshop does.
> It would be incorrect to interpret this image as RGB.
How does Photoshop treat a second alpha channel? Does it actually get used for anything?
Alpha channels are just alpha channels - they get loaded and the user can do what they want with them.
Only transparency (associated alpha) has any special meaning.