The Method of Image Acquisition on Metal Label Pressed Protuberant Characters Based on Moir é Contour

The image of pressed protuberant characters on metal label is formed by the difference of reflectance. It is very difficult to obtain the high quality binary image of such character directly. This paper has presented a novel method of image acquisition on metal label pressed protuberant characters based on moire contour. At first, the principles of moire contour were analyzed; secondly, the experiment parameters were designed by using of shadowing moire equipment and pressed characters´ height, and the moire image of metal label was captured through experiment by using of CCD camera. The binary image of pressed characters was output using moire fringe image modulated by the characters´ height as input image contrast enhancing, complement, middle filter, automatic threshold etc.. The binary image of pressed characters was obtained using image pretreatment by way of image of continuous recognition. At last, the binary images of the pressed character obtained based on moire contour was compared with those based on the normal methods. The experiments proved that the former is better than the latter