US Patent 7817861 Detection of image spam

A method of detecting spam images in electronic objects such as emails includes compressing images extracted from the electronic object into a common representation using a lossy compression function and determining if the compressed forms of the extracted images are identical to the compressed form of any known spam image from a corpus of known spam images, which compressed forms are the known spam images compressed into the common representation using the lossy compression function. The electronic objects are signalled as embedding a spam image on the basis of a compressed form of an extracted image extracted from an electronic object being determined to be identical to the compressed form of a known spam image.