E = | m(x, y) - m(x1, y1) | (1)
m(x, y) = gray level of the pixel with co-ordinate (x, y)
If E > certain predetermined threshold value, then this will
be assumed as point detection. The gradients of the variation of
gray level are calculated for adjacent points in order to find
edges. The magnitude difference of X-gradients and Ygradients
are computed for nearby points. Let the variation of
magnitude for two adjacent points be ¨G and the variation of