CMC Method
To reduce the effect of correlation from the invalid correlation area, the CMC method divides the image data into correlation cells. In this experiment, the cell size is set as (100 × 100) pixel or (0.49 × 0.49) mm2. The resulted number of cells is (7 × 7).
For a pair of images A and B, every valid cell divided from A is correlate to every rotated image B. The rotation range is ±30° with 3° increments. Each correlation cell in image A scans the whole area of each rotated reference image B to find the best matching position. Once the procedure is completed, the similarity metrics consisting of the CCFmax value, the registration angle θ and the translation distances in x and y are recorded.