1. A method of segmenting an object in a digital image having a plurality of pixels, comprising: selecting a foreground node located in the object and a background node outside of the object; determining a plurality of coefficients, each one of the plurality of coefficients being a function of the relative image data associated with two of the plurality of pixels, each pixel having a vector of color values; storing only diagonals of a Laplacian matrix related to the plurality of coefficients as a texture and computing a main diagonal from the stored diagonals for processing by a graphics processing unit; solving up to 4 different systems of linear equations simultaneously at the computational cost of one system based on a random walker segmentation with the Laplacian matrix, the systems of linear equations including the plurality of coefficients and being dependent on the foreground node and the background node, using a texture processing architecture of the graphics processing unit; and determining a potential for each pixel in the plurality of pixels from the solving a system of linear equations.