1. A method of determining a sought object contour in a digital microscope image, which includes a plurality of image elements and reproduces a biological material, the method comprising: 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 comprise 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 comprise 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 the second gradient vector components.