Methods, program products and systems for automatically trapping drop shadows. For at least one segment incident to an atomic region which includes a drop shadow, and for each side of the segment, determining a first flattened color of the side's incident atomic region, and if the atomic region includes a drop shadow, additionally determining a second flattened color omitting the color of the drop shadow. An effective neutral density from the side's first flattened color is determined and, if the side has a second flattened color, the side's second flattened color. The two atomic regions incident to the segment are trapped based upon the effective neutral densities for the respective sides.