Segmentation of striation patterns using illumination series

In this contribution, an image processing method is presented that uses an illumination series to robustly segment striation patterns from mainly isotropic background areas. The illumination series is obtained with a spot illumination whose azimuth is varied systematically. The strategy is based on the characteristics of the local contrast with respect to the azimuth of the illumination: Whereas pronounced maxima of the local contrast can be observed when the striae are illuminated perpendicularly, an isotropic background texture shows less distinct maxima for random azimuth angles. The qualification of the approach is demonstrated on the segmentation of faint tool marks in forensic science. Experimental results show that the methodology ensures the correct segmentation of such marks.