2002.03.07 18:58 "Re: Photoshop Alpha Channel", by James Burgess

1. Open a blank image
2. Draw anything on it. Make it small enough that you can see the background checker pattern.
3. Save it as a PSD.
4. Save it as a TIFF.
5. Open both the PSD and TIFF and compare them. The PSD will maintain the alpha channel while the TIFF file will have been merged over white with no sign of transparency.

Peter,

As an independant observer I just tried this. If you repeat your experiment above with PhotoShop 7 or 6 you will get the result I think you thought you should. Don't know about 5 though. You do to have turn on "Advanced TIFF options" in preferences whioch then lets you check "Save Transparency". Looks to me like the alpha is even pre-multiplied.