SEGMENTATION of ROAD SIGN SYMBOLS using OPPONENT-COLOR FILTERS
Yutaka Ishizuka, Yuzo Hirai · 2004
A novel algorithm for the recognition of Japanese road sign symbols with red annular boundaries is proposed. After detecting a red annular object using HSV color coordinates, a biologically inspired opponent-color filter is applied to extract the symbol parts of road signs. By applying discriminant analysis to the filter output, the inside region circumscribed by red annular boundary can be extracted. By applying the discriminant analysis again to the inside region, the symbol part of road sign can be segmented. The extracted symbol is classified by a decision tree and recognition rate of about 96 % was achieved for real road video images. It is shown that the opponent-color filter can lead to accurate recognition even for small and degraded road signs in video images.