Abstract: Images of imprints, e.g. made by items of footwear, are displayed on a computer screen. Any identification features A-D which are present in the image are tagged and the length of all the lines 1-6 joining the tagged features are calculated and the distance information is added to a database together with the images themselves. The polygons defined by the lines 1-4 are independent of the positioning or orientation of the image and are used to retrieve images likely to originate from the same article by applying search criteria which retrieves records containing distances falling within selected bands.

Abstract: A digital image is captured from an imprint left at the scene of a crime with a predetermined reproduction ratio. Suitable capture apparatus comprises a digital camera 1 supported in a stand 2 above the image 3. The captured image is displayed on a computer screen, cropped to a predetermined size, and the co-ordinates of any unique identification features in the image are recorded in computer memory, preferably together with information on the size and nature of such features. The sets of co-ordinates are stored in a database and compared to identify similar sets of co-ordinates likely to originate from the same article. The data can also be compared with a second database of co-ordinate data taken from the footwear of known offenders in order to link crimes with offenders.