1. A method of segmenting a composite image of pixels of a physical document into a number of fields corresponding to lay-out elements of the image of the physical document, the pixels having a value representing the intensity and/or color of a picture element, the method comprising: analyzing the pixels of the image as either background pixels having a background property indicative of a background of the image or foreground pixels not having said background property; detecting in the image any foreground separator elements that are objects in the foreground of the image having a pattern of foreground pixels; replacing the pixels of the detected foreground separators by pixels having the background property; constructing separating elements corresponding to rectangular areas of adjacent pixels of the image having the background property; and constructing a graph representing the lay-out elements of the image of the physical document by defining vertices of the graph on the basis of intersections of separating elements that are substantially oriented in predetermined separation directions, defining edges of the graph between the vertices corresponding to the separating elements, and defining field separators corresponding to the edges of the graph.