1. A method of processing postal items, which method comprises the steps of (a) causing the postal items to advance in series past a camera for the purpose of generating an image of one face of each postal item, which face bears postal address information, (b) filtering the image of a current postal item for the purpose of isolating, in the image, at least one region of interest (ROI) containing the address information, (c) sending the filtered image to an automatic recognition unit for automatically recognizing postal addresses by means of OCR so as to extract the postal address from said filtered image and so as to direct the current postal item to a sorting outlet, and (d) causing a card of the “separator” type to advance past the camera, which card has a face on which a boundary of said region of interest (ROI) is represented graphically, so as to construct a filter mask.