1. A method for segmenting an image comprising: receiving an input image to be segmented; and with a processor: for each label in a set of labels, assigning unary potentials to pixels of the input image, the unary potentials being based on information for a first channel in the image; for each of pairs of labels in the set of labels, assigning pairwise potentials for neighboring pixels of the image, the pairwise potentials being based on information for a second channel in the image, different from the first channel; optimizing an objective function over pixels of the input image to identify labels for pixels of the image from the set of labels, the objective function being an aggregation of ones of the unary potentials and pairwise potentials; and segmenting the input image based on the identified labels.