Research On Printing Image Quality Detection Technology Based On HALCON

Abstract:The edge extraction and template matching are the key points in product printing defect inspection as they have high demand of positioning accuracy. Scholars have proposed various fast template matching methods,but traditional template matching algorithms which base on the gray value have the problems of complexity and high sensation on image complexity and image rotation.To solve above problems, the thesis proposes a new shape matching algorithm based on edges, combining with images characteristics, designs and implements the algorithm. It is proved that the algorithm can meet the requirements of industrial production by testing.The paper mainly completes the work as follow:Firstly, it introduces edge extraction algorithms, analyze the operating princple respectively. The results shows the Canny filter can meet the requerements.Sencondly, it proposes and implements a shape-based template matching algorithm. First of all, it extracts the edge points of template image using Canny operator, then using the Sobel operator filters images. The results are the template image position vector and the gradient vector of edges, that is the template shape model. Similarity measurement uses the inner product of the template edge points and the corresponding points of image search region. Analysis shows that the method resists disturbing from noise and not sensitive to small angle rotation.Thirdly, it implements the above shape-based template matching algorithm by using Halcon. First, the matching region based on the region features is chosen.Then, fast image matching in the approach of the shape-based matching is realized. At last, the improved difference-matching algorithm to detect the printing defects is used. The result of the experiment shows that the approach can choose the proper matching regions from the printing image automatically, match the images with high accuracy and speed.Finally, the paper analyzes the hardware and software of the printing quality check system, which is developed by Halcon and VC2012 software development platform. The system can check for smears and splashes as well as for missing or misaligned parts of the prints. But there are many aspects to be improved in order to satisfy actual application. At last, some notions of improvements have been given.