Replace/ update image in animation - scripts?

I am looking for a good way replace one or more images in an already made animation. You could of course update direct in the scene but if you got an updated design of the head etc how to update that if you have several scenes to do it in.

And is it possible to replace several images at once.
I read about a script here on the forum a while ago but cant find that post.

/ Mattias
Harmony Adv.