1. A computer-implemented method, comprising: generating an initial border mask from an object mask, wherein the object mask indicates an initial boundary selection for a foreground object in an image, and wherein the initial border mask specifies a maximum region outside the object mask for a border of the foreground object in the image; generating an initial foreground probability map for the initial border mask according to a Gaussian mixture color modeling technique applied within the initial border mask, wherein the initial foreground probability map indicates, for each pixel of the image within the initial border mask, a probability that the pixel is a foreground pixel; smoothing the initial foreground probability map according to a geodesic smoothing technique to generate a smoothed foreground probability map, wherein the geodesic smoothing technique smoothes the probability for each pixel in the initial foreground probability map according to location of the pixel relative to at least one boundary of the initial border mask; determining a foreground boundary within the initial border mask from the smoothed foreground probability map; and generating a variable-width border mask for the foreground object according to the determined foreground boundary, wherein the variable-width border mask is defined by an inner boundary and an outer boundary, wherein the determined foreground boundary corresponds to the outer boundary of the variable-width border mask, wherein the variable-width border mask specifies a variable-width region of the image outside the object mask for the border of the foreground object.