Otsu‟s method is nonparametric and unsupervised method of automatic threshold selection for image segmentation. An optimal threshold is selected by the discriminant criterion [10], namely, so as to maximize the separability of the resultant classes in gray level. The procedure is simple, utilizing only the zero and the first-order cumulative moments of the gray level histogram. There are three types of discriminant criteria and the one used in this paper to obtain an optimal threshold value is shown in Eq. (2).