Extraction of accurate stomach contour from X-ray images of barium filled stomachs

The extraction of an accurate stomach contour from radiograms for mass screening is described. The extraction is not easy because the shape and the brightness of stomach change considerably depending on the individual and the input conditions. The proposed method first obtains an approximate region, and then tracks obvious local maxima of the differentiated data in a small search area near the region to get an accurate stomach contour. If the local maximum is not found, the search area is made larger. In case it is not found even in a larger area, the stomach contour is determined by using a reference direction derived from the approximate region. The abnormalities detected from the resultant stomach contour have been satisfactory