Fig. 1. Schematic description of morphologic features.

Area and perimeter are calculated from ROI drawn on image. Ellipse fitted to given ROI is obtained. Then, major and minor axes of ellipse and convex area are calculated. Based on these values, morphologic features (circularity, roundness, aspect ratio, solidity, compactness, and others) are calculated according to equations shown in Figure 1. Values of morphologic features for angular and rod shapes are compared with those for complete circle, which has value of 1 for all morphologic features. ROI = region of interest