A method extracts an alpha matte from images acquired of a scene by
cameras. A depth plane is selected for a foreground in the scene. A
trimap is determined from a set of images acquired of the scene. An
epipolar plane image is constructed from the set of images and the
trimap, the epipolar plane image including scan lines. Variances of
intensities are measured along the scan lines in the epipolar image, and
an alpha matte is extracted according to the variances.