An
iris out is a
technique for
fading to black. It is used extensively in
cartoons and
animations. At the end of a cartoon short, the cartoon fades to black with a black background with a transparent circle that slowly closes to all black, similar to a
pupil closing.
The effect is made by superimposing a mask or matte of sequentially smaller circular cutouts over the animation action. The effect is combined with the animation reel using an optical printer.