1. A method for extracting an alpha matte from a color input frame using a computer system having a graphics processing unit, comprising the steps of: (a) inputting the input frame as a set of frame pixels in a multivariable color space digital format to the computer system; (b) applying computer implemented instructions for bilayer segmentation of the input frame to create an initial trimap for the input frame which partitions the frame pixels into initial estimates for a background region, one or more foreground objects and a boundary set; (c) the computer system having a selected multichannel Poisson equation; (d) the computer system iteratively solving the selected multichannel Poisson equation for the frame pixels within the boundary set, until the earlier of (A) a first decision criteria assigning all such frame pixels to either the foreground objects or the background region if the first decision criteria is met or (B) a second decision criteria to proceed notwithstanding that the first decision criteria has not been met for all pixels; wherein the selected multichannel Poisson equations treat each of a plurality of the dimensions within the multivariable color space as a channel; (e) the computer system generating an alpha matte for the input frame in which the frame pixels assigned to the background region set in steps (b) and (d) are assigned a background number, the image pixels assigned to the foreground objects in steps (b) and (d) are assigned a foreground number, and the image pixels not so assigned are each assigned a boundary value representing a percentage by which such frame pixel may be in the foreground or the background.