This is a simple, but effective way of trying to find a point with the optimal block. During the horizontal stage, the point on the horizontal direction with the minimum distortion is found. Then, starting with this point, the minimum distortion in the vertical direction is found. The algorithm may be described as follows :
Step 1 : Pick three points about the centre of the search window. (horizontal)
Step 2 : If the smallest distortion is for the centre point, start the vertical stage, otherwise look at the next point in the horizontal direction closer to the point with the smallest distortion (from the previous stage) Continue looking in that direction till you find the point with the smallest distortion. (going in the same direction, the point next to it must have a larger distortion)
Step 3: Repeat the above, but taking points in the vertical direction about the point that has the smallest distortion in the horizontal direction.
One particular search path for the algorithm is shown in figure 8. This search algorithm requires very little time, however the quality of match is not very good.