1. A method for classifying a pixel in a digital image, said method comprising: receiving a first classification map, wherein said first classification map identifies candidate pixels belonging to a first class in a digital image; receiving a first pixel location in said first classification map, wherein said first pixel location in said first classification map corresponds to a first pixel location in said digital image; calculating a first color estimate corresponding to said first pixel location in said digital image, wherein said first color estimate is a summary of the colors of a plurality of pixels belonging to said first class located in a region proximate to said first pixel location in said digital image; determining a validity state associated with said first color estimate, wherein said validity state is determined to be a state associated with an invalid first color estimate when a second plurality of pixels associated with said region does not contain at least one pixel identified as belonging to said first class according to said first classification map; calculating a first color difference from said first color estimate and the color of the pixel in said digital image at said first pixel location in said digital image; and refining said first classification map at said first pixel location in said first classification map based on said first color difference and said validity state.