REGRESSION

        REGRESSION Nmin [/RANGE [X Xmin Xmax] [Y Ymin Ymax]]

    Computes linear regressions in a image which is the correlation  of  two
    coincident images. The regression lines
           Y = A * X + B   and    X = A'* Y + B'
    are computed assuming the weight of any (X,Y) is the value of the  pixel
    at  X,Y. Nmin is the minimum pixel value considered as significant.