I really don't know if I'd do what you're suggesting in Photoshop though. Seems like an awful lot of work. Premiere and After Effects I believe allow you to set a color in a video as a "green screen", allowing you to place other elements in the color that is dropped out. I'm pretty sure you don't have to do it frame by frame but I don't have the ability to check that right now.

What I was suggesting to you via IM was that you consider doing this if you have Premiere or After Effects:

If the background doesn't change, only the foreground (ie. characters and props), then render a single image of your background. Then do a seperate render of the animation for the characters (wihtout background) in the scene and a sepereate render of the animated props (without background). Use the green screen effect and layers in the program to composite your video with the background elements.

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Now, if you're stuck with just Photoshop (that came out wrong...sorry), then take a look at the automated tab in the file menu. There's something called BATCH, which allows you to automate certian things. I have not used it more than once, so I can't give you any real details on it but there should be info in the manual, helpfiles, or on the net on how to set it up so it does what you need or at least some of what you need.

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Combustion, another program designed just for compositing, is another possiblity if you can afford it. There may even be a demo available that you can use. EDIT: I should mention I use P7. Don't know if they changed the layout for CS or CS2.

Message edited on: 05/15/2005 10:56