Research on correction and recognition of QR code on cylinder

In the actual application, the QR code was affected by the collection conditions, environment and surface of substrate, which would cause a series of defects such as noise pollution, local highlight and geometric distortion. These defects would lead to the reduction of recognition rate. The research of preprocessing, area detection, extraction and correction processing for these defects was based on the principle of image processing. Methods were proposed to optimize the QR code and improve the recognition rate. According to the basic principles of digital image processing, the processing technology of QR code was analyzed. The algorithm of threshold segmentation, the molecular block Otsu method was used to deal with the uneven illumination. Based on the special structural features of the position detection pattern, the QR code was detected and extracted from the image. The method of anti-perspective transformation was used to correct the QR code with geometric distortion. The QR code printed on the surface was fitted to surface area, and the corrected graphic was obtained. Then grayscale was interpolated into the corresponding coordinates to get the corrected QR code. The jagged and virtual dots in the image were eliminated by the morphological close operation. The results showed that the Otsu method that combined with the principle of threshold segmentation was applied to process the QR code with uneven lighting and low brightness.