Another set of quantitative measurements can be obtained from the gray-level co-occurrence matrix (GLCM) which represents a second-order statistical modality that provides information related to the spatial relationship between pixel intensities in each image . The GLCM matrix is built based on the number of occurrences of a certain pair of pixels, at a specific distance between pixels. Each result is divided by the total number of elements to calculate a probability. Such a matrix can be calculated for any distance between pixels either horizontally (0°), vertically (90°), or diagonally (45°,135°). Because we observed only small variations between the values calculated according to different orientations, we report here the average value for the results obtained for the four orientations. We extract two features of the GLCM: energy (or the angular second moment) and correlation.