Chroma Key on Multiple Images. does anyone know how?

I'am working with short animated clip, in FCE 4 actually, and i need to make animated character to move in real footage. I have finished ~ 700 pictures of that character, so what i don't understand is, how to delete white background out of so many pictures... Any suggestions? (p.s. I can create independent movie clip out of these images and then delete white background, but in this case i will lose quality, so it is my plan b)