Methods, apparatus, and machine-readable media for segmenting and enhancing images are described. In one aspect, gradient magnitude values at respective pixels of a given image are determined. The gradient magnitude values are thresholded with a global threshold to produce thresholded gradient magnitude values. The pixels are segmented into respective groups in accordance with a watershed transform of the thresholded magnitude values. A classification record is generated. The classification record labels as background pixels ones of the pixels segmented into one of the groups determined to be largest in size and labels as non-background pixels ones of the pixels segmented into any of the groups except the largest group.