License plate recognition is a wide demanding image processing application. We have explored the possibility by using wavelet transform to detect the location of a license plate for non-moving vehicle. The license plate is designed to have high contrast differences which can be easily seen by human eyes. The decomposed high frequency component of wavelet transform extracts high contrast part of license plate. The large magnitude peaks of high frequency component indicate the edges of the foreground character and white background. We search these edges on the horizontal and vertical directions separately. By judging the similarity of neighboring pixels of edge points, we successfully detect the location of license plate.
