EXTRACTING A MATTE OF A FOREGROUND OBJECT FROM MULTIPLE BACKGROUNDS BY TRIANGULATION

A method for pulling (extracting) a matte of an image of a foreground object from a composite image, using a computer. An image of the foreground object is recorded over at least two backgrounds having arbitrarily different coloring. Each point of one background must have a color that is different than the color of a corresponding point in the other backgrounds. The images may be recorded with an analog camera and digitized with a scanner or recorded with a digital camera. Images should be registered during recording and digitization to eliminate misalignment of corresponding points in each recorded image. A triangulation of corresponding points of each recorded image is performed so that an alpha value (opacity) and a set of color coordinates for each point of an uncomposited image of the foreground object may be determined using either a difference of sums technique or a least squares technique. To facilitate the triangulation, images are recorded of each background alone, without the foreground object. The lighting and distances between the camera and object, and between the object and backgrounds should remain constant during the image recording process.