Automatic multithreshold selection

Abstract

A recursive technique for multiple threshold selection on digital images is described. Pixels are first classified as edge pixels or nonedge pixels. Edge pixels are then classified, on the basis of their neighborhoods, as being relatively dark or relatively light. A histogram of the graytone intensities is obtained for those pixels which are edge pixels and relatively dark and another histogram is obtained for those pixels which are edge pixels and relatively light. A threshold is selected corresponding to the graytone intensity value corresponding to one of the highest peaks from the two histograms. To get multiple thresholds, the procedure may be recursively applied first using only those pixels whose intensities are smaller than the threshold and then only those pixels whose intensities are larger than the threshold.