Comments on Picture thresholding using an iterative selection method

T.W. Ridler and E.S. Calvard (ibid., vol.SMC-8, p.630-2, Aug. 1978) presented a method of picture thresholding that was further mathematically developed by H.J. Trussel (ibid., vol.SMC-9, p.311, 1979). The principle of this method is to evaluate the unique threshold T for any image with a bimodal histogram. The present paper reinterprets the procedure as an algorithm designed to optimize the conversion of a multiple gray-level picture to a bimodel picture while maintaining as closely as possible the average luminance of the picture. >