I know (as with nost things) this can be automated by creating an action. I think this is a common enough thing that most people would benifit from having it preset in some way. Ever copy then paste only to find out that the white background didnt come with it and you have all these wonky edges to fill in. Why not add a feature that places a white background on a new layer beneath your work then merges the current layer with this to create a solid background?
AdChoices
