Gray-Level Co-occurrence Matrix

This matrix is a tabulation of how often different combinations of pixel brightness values occur in an image according to a particular displacement vector that shows the direction towards we look for the occurrences. We used a GLCM normalization that expresses the probability of occurrence.

• Each Frame is divided into Macroblocks (16x16 pixels).
• Each GLCM is computed according to a displacement vector d.
• GLCM is computed for each Macroblock.
• Different statistics are calculated and placed into the feature vectors. These vectors are the inputs for the segmentation algorithm
• •4 main directions have been used so as to compute the occurrences: 0° or (1,0); 45° or (1,1); 90° or (0,1); 135° or (-1,1).

Example of a GLCM matrix for a 4x4-pixel Macroblock, using d=1 and direction 0º.