“…Based on methods used in the literature, we categorized the segmentation methods into threshold-based, contour-and transform-based and clusterbased methods. In threshold-based approaches, use of Otsu's thresholding [21,26,32,41,43,44,52,54,74,76,81,85,89,92,95], incremental thresholding [59,60], and multiple thresholding [22,88] were reported for extraction of ROI. Contour-based segmentation includes active contour methods [29,59,101] and Sobel edge detectors [21].…”