Blue Screen Matting

A classical problem of imaging--the matting problem--is separation of a non-rectangular foreground image from a (usually) rectangular background image--for example, in a film frame, extraction of an actor from a background scene to allow substitution of a different background. Of the several attacks on this difficult and persistent problem, we discuss here only the special case of separating a desired foreground image from a background of a constant, or almost constant, backing color. This backing color has often been blue, so the problem, and its solution, have been called blue screen matting. However, other backing colors, such as yellow or (increasingly) green, have also been used, so we often generalize to constant color matting. The mathematics of constant color matting is presented and proven to be unsolvable as generally practiced. This, of course, flies in the face of the fact that the technique is commonly used in film and video, so we demonstrate constraints on the general p...

• Type: Conference
• Year: 1996
• Where: SIGGRAPH
• Authors: Alvy Ray Smith, James F. Blinn
• Keywords: Backing Colors, Computer Graphics, Constant Color Matting, Foreground Image, SIGGRAPH 1996