1. A method of comparing in a processor a logo image with a search image so as to detect the presence in the search image of a logo portrayed in the logo image; comprising the steps of: determining the positions of logo edges within a sequence of logo edges along a first spatial sampling direction in the logo image; representing said logo edges by ratios of distances between the respective logo edge and a plurality of preceding logo edges; determining the positions of search edges within a sequence of search edges along a first spatial sampling direction in the search image; representing said search edges by ratios of distances between the respective search edge and a plurality of preceding search edges; and comparing said represented logo edges with said represented search edges.