Content-Based Information Retrieval from Forensic Image Databases

A tool mark imaging system database (named TRAX) has been developed. The database is filled with video-images and alphanumeric data about the tool marks (width, kind of tool mark, etc.). The angle of the tool with the surface, the material of the surface, and the way the tool is moved on the surface, influence the shape of the striation mark. A new algorithm, referred to as the adaptive zoom-algorithm for extracting a representative signature of this striation mark has been developed. The similarity measure is based on the Standard Deviation of the Grey-value Differences. Furthermore, the comparison of these signatures should also deal with wear of the tool and variations between test marks and the mark found at the scene of crime. For that reason the adaptive zoom-algorithm is also used for the comparison of signatures. The development is based on the way a tool mark examiner conducts the comparison. The algorithm works well for side light images of deep and complete striation marks and is implemented in TRAX. A test showed that by using 3D images of striation marks, the results of correlation improved. 3.