The Importance of “Clean Plate”

by Dyske Suematsu  •  October 5, 2006

So called “clean plate” is used by keyers like Ultimatte to intelligently separate foreground elements from the background. In order for this to work effectively, it has to be identical to the actual footage minus the foreground elements. If it is slightly off, it becomes virtually useless.

Some cameramen do not seem to understand the significance of this. They change the focus slightly and think, “What’s the big deal?” Well, it is a big deal. It needs to match exactly; pixel for pixel. In the example of below, not only the positions of the props do not match, but also the shades of green are different. (The actual scene on the left, and clean plate on the right.)

Exhibit A

If possible, get the actors to clear the frame after every take. If this compromises their acting, try not to touch the camera at all. No focusing, zooming, repositioning. And, do not touch the lights either.

In some instances, the key light for the actor spills into the background, and the presence of the actor alters the shade of the background. Try to avoid this if possible.

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