So. Belkasim et al., NEW METHODS FOR CONTOUR-DETECTION AND AUTOMATIC THRESHOLDING, Canadian journal of electrical and computer engineering, 20(4), 1995, pp. 165-171
This paper presents two new approaches for optimum thresholding of gra
y-level images. The first algorithm utilizes an iterative thresholding
scheme in conjunction with a golden-section optimization technique to
determine the optimum threshold that maximizes the number of contours
and the number of pixels in the contours. The second algorithm uses t
he same optimization technique to determine the optimum threshold that
maximizes the average perimeter of the scene image.