System and method for detecting document alteration

摘要

A system and method for detecting alteration of documents having a photo-luminescent security layer. The method comprises; forming a photo-luminescence image of the document to reveal irregularities in the photo-luminescent security layer during transportation of the document past a photo-luminescence scanner 4 which illuminates the document with ultraviolet radiation, storing the photo-luminescence image in a memory 26 and analysing the photo-luminescence image using a processor 24 to determine whether the irregularities actually correspond to alterations made to the original document. By storing images, the analysis of the images may be performed even if the original document is no longer easily retrievable. This is particularly important in the context of clearing cheques. A further embodiment comprises forming a second image of the document under illumination with visible light which is compared to the photo-luminescence image.