Alpha Channel from B&W layer

[Lesley_Flanigan@adobeforums.com]

I know how to create an alpha channel and paint in your mask using black and white. My question is this: How can you take an already black and white layer, and convert its detailed information into an alpha channel? I can do this in After Effects pretty easily, but can't find a way to do it using Photoshop 7.

Thanks for any ideas...

[Ed_Hannigan@adobeforums.com]

If CMYK turn off all other layers and duplicate the Black channel. If RGB any of the channels will do. If Grayscale duplicate Gray.

[jonf@adobeforums.com]

Are copy the b/w layer, create a new alpha channel, and paste. The possibilities are endless.