Road signs shapes detection based on Sobel phase analysis

This paper presents a method for triangular and rectangular shapes detection in a road sign recognition system based on a three step algorithm: color segmentation, shape detection and neural network classification. The shape detector is based on the evaluation of the Sobel edges and Hough images in a region of interest detected by the color-based stage. During the tests performed the shape detector shows its robustness to rotation, occlusion and deformation, despite a 10% increasing of total computational times compared with that requested by the pattern matching.