APPARATUS FOR DETECTING POSITION OF NUMBER PLATE

摘要

PURPOSE:To make it possible to use a threshold value fixed by binarization in determining the position of a number plate, by binarizing the differential value of an image signal and extracting the area having a large number of changes of the binarized value as a characteristic point. CONSTITUTION:The image signal of a vehicle front part containing a number plate from a TV camera 13 is stored in a frame memory 3 through a distributor 2 and inputted to a differentiation circuit 4. The output of the circuit 4 is binarized on the basis of a fixed threshold value by a binarizing circuit 5 to be stored in a differential binary image accumulation part 7 through a distributor 6. A characteristic extraction circuit 8 counts the number of changes in the horizontal direction of the differential binary image and extracts the number of changes within a predetermined distance as a characteristic point when said changes are a predetermined value or more to store the same in a characteristic buffer 9. CPU 10 detects the position of the number plate from the pattern of the characteristic point. Whereupon, the threshold value fixed by the binarization of the image differential value can be used and characteristic extraction can be performed at a high speed by hardware.