AUTOMATIC THRESHOLDING BASED ON HUMAN VISUAL-PERCEPTION

An automatic thresholding method based on aspects of the human visual system which preserved edge structure in images is proposed. We first determine edge thresholds based on human visual perception, and then u se these edge thresholds to find several edge intervals. From these ed ge intervals, we find the threshold value(s) at which most edge inform ation is preserved in the thresholded image. A bilevel thresholding al gorithm is first described, and then two multilevel thresholding algor ithms called N(m)-multilevel thresholding and mN-multistep thresholdin g arc derived through a slight modification of the bilevel thresholdin g algorithm. The multistep thresholding algorithm directly uses bileve l thresholding sequentially to select m threshold values one by one so as to speed up the thresholding process. The proposed thresholding me thod is simple, requiring neither an iterative operation nor edge dete ction.