2002.03.06 00:46 "Re: Photoshop Alpha Channel", by Peter Montgomery
I'm not sure if this is what Phil was referring to, but PhotoShop has the most pathetic handling of alpha I can imagine. Here's a simple one:
- Open a blank image
- Draw anything on it. Make it small enough that you can see the background checker pattern.
- Save it as a PSD.
- Save it as a TIFF.
- 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.
This is inexcusable. I should be able to save a TIFF, PNG, or TGA and still have my alpha channel. Of course, if you open a TIFF file that has a proper associated alpha channel, PhotoShop will properly display the image. Too bad you then have to save it as a PSD in order to maintain the alpha.
Want to see how it's supposed to be done? Try the GIMP. Everything works correctly. I'm not going to get into a religious war, but simply put, when a free program knows how to handle alpha and the "industry standard" doesn't, I stop buying the "industry standard." More specifically, PhotoShop's non-existent handling of the alpha channel makes it completely unusable for my work in the film industry. I don't want to be forced to use the cumbersome PSD format when I can save much smaller PNG files properly in the GIMP. Oh yeah, you're not alone. PaintShop Pro also doesn't have a clue about how to handle alpha. Too bad. Adobe might have gotten me to keep buying the program if they had knew how an alpha channel is supposed to work.