im_dif_std - calculate the mean and the standard deviation of the
difference image for a given displacement vector
int im_dif_std(im, xp, yp, xs, ys, dx, dy, mean, std)
int xp, yp, xs, ys;
int dx, dy;
double *mean, *std;
im_dif_std() calculates the mean and the standard deviation of the
difference image created by the displacement vector (dx,dy) on the box
(xp,yp;xs,ys) defined on the image pointed by im. More specifically
the difference image is of an image given the dispacement vector (dx,
dy) is defined as follows: For each point of the original image, the
start of the vector (dx,dy) is set on that point. The difference image
at this point is defined as the difference of the values pointed by the
vector (end value - start value). The function returns the mean and
the standard deviation of the difference images measured on the area
(xp,yp;xs,ys) of im.
Input im should be one band unsigned char image and it should have been
set by a call to im_mmapin(3) or im_setbuf(3).
The function returns 0 on success and -1 on error.
N. Dessipris - 10/05/1991
10 May 1991