Since the source of the proposed mask is a grayscale image, you can
either copy the background layer (or the black channel), switch to
the destination image, click the channels palette, create a new
channel, and paste. This will populate the new alpha channel with
the grayscale image.
One way to apply your new mask is to then click the RGB (or CMYK if
applicable) channel so the composite image is displayed. Switch
back to the layers palette, select the layer to which you want to
apply the selection (or create a new layer), SELECT/LOAD
SELECTION... and select your newly loaded alpha channel.
Then apply whatever effect(s) you want. The effect(s) will be
applied according to the characteristics of the mask.
Is this where you wanted to go?
Hi,
I was wondering if there was any way to use a grayscale image in
photoshop as a mask for another image.
Thanks