Abstract
In this study, a new interpolation method was proposed to enhance low resolution license plate images. We believed that the gray value of the image is close to the average gray value of an area, instead of the gray value of a certain point. With the novel approach, a pixel is divided into a 2x2 area first. The gray value of the original pixel and neighbors of the original pixel are all taken into account. When the gray level in a certain direction increased or decreased gradually, the difference in gray level between original pixel and both sides of the original pixel are calculated. If the difference at a certain side is smaller, the new pixel at side is assigned to the gray level of its neighbor, while the average of the gray level is equal to that of the original pixel. After considering horizontal, vertical, and orthogonal directions, the gray levels for the new 2x2 area are determined. In this study, the new approach and several static reconstruction methods are tested. Images from image degradation model and those taken from camera directly were used to test these approaches. Based on the test results, the new method shows promising potential for improving the license plate recognition.