关键词: 边缘信息提取, 印刷电路板缺陷图像, 二阶曲线拟合, 阈值比较法, 最小二乘法, 模式聚类, Canny算子

Abstract: In order to extract the defect image edge information of printed circuit board better, an edge information extraction method for the printed circuit board defect image based on the combination of the second order curve fitting, pattern clustering and threshold comparison method is proposed in this paper. Firstly, the basic principle of least squares method is analyzed. Secondly, the fitting method by adopting second order curve fitting to intercalate threshold to obtain the rough image edges is proposed, and its basic principle is analyzed in detail. Finally, by using the threshold comparison method based on the pattern clustering, the image edge points are obtained and the noisy edge points are eliminated by selecting proper threshold to intercept the fitting curve, and the defect image edges information can be obtained by joining each image edge point. The edge information extraction experiment by using the four defect images of printed circuit board acquired by microscope and CCD is actualized. It can see from the subjective results that the images edge is more continuous by adopting this method, and it has lesser noise points. From the objective effect evaluation results, the image information entropy is bigger than that of other methods mentioned in this paper. The experimental results show that it can extract better the defect image edge information of printed circuit board because of the advantages of the two order curve fitting, the pattern clustering and the threshold comparison method are merged.

Key words: edge information extraction, printed circuit board defect image, second order curve fitting, threshold comparison method, least squares method, pattern clustering, Canny operator