A method is disclosed for determining a sought object contour in a digital
microscope image, which includes a plurality of image elements and
reproduces a biological material. The method includes assigning edge
values to at least a first subset of the image elements in the image;
assigning values of a first gradient vector component whose values each
includes a first linear combination of edge values of some surrounding
image elements to at least a second subset of the image elements in the
image; assigning values of a second gradient vector component whose
values each include a second linear combination of edge values of some
surrounding image elements to at least a third subset of the image
elements in the image; and calculating an estimate of the sought object
contour based upon values of the first and second gradient vector
components.