基于降采样和改进Shi-Tomasi角点检测算法的PCB图像拼接

针对大型多重复单元PCB图像拼接耗时长、拼接错误率高等问题,提出了一种快速鲁棒的图像拼接方法.对采集到的高分辨率PCB图像进行降采样,基于人工选点精准获取含重叠区域的图像单元作为配准区域;引入抑制半径的方法对Shi-Tomasi角点检测算法进行改进,使提取出的区域特征点分布更加均匀;使用暴力匹配方式分别对区域特征点进行粗匹配并通过RANSAC算法剔除误匹配点对后获得配准系数矩阵;结合仿射变换公式推导计算出原图像的配准系数矩阵,根据配准系数矩阵对待拼接的图像进行融合,得到完整的PCB拼接图像.实验结果表明,所提出的PCB图像拼接方法,加快了PCB图像拼接的速度同时也提高了特征点匹配精度,在对图像降采样8倍下,改进的Shi-Tomasi算法较传统的Shi-Tomsi算法和Harris算法在匹配正确率上分别提高了7.8％和4.0％,验证了该方法的可行性.

PCB image stitching method based on down-sampling and improved Shi-Tomasi corner detection algorithm

Aiming at the problems of long time consuming and high error rate of  large multi-repeating unit PCB image stitching, A fast robust image stitching method was proposed. The collected high-resolution PCB images were sampled down, and image units containing overlapping areas were accurately obtained based on manual points as registration areas; The Shi-Tomasi corner detection algorithm was improved by introducing the suppression radius method to make the extracted regional feature points more evenly distributed; The violence matching method was used to carry out the rough matching of the regional feature points respectively and the registration coefficient matrix was obtained after removing the mismatched point pairs by RANSAC algorithm. Combined with affine transformation formula, the registration coefficient matrix of the original image was deduced and calculated. According to the registration coefficient matrix, the stitched images were fused to obtain a complete PCB stitched image. Experimental verification shows: the proposed image matching method accelerates the speed of large PCB image stitching, and also significantly improve image registration precision at the same time, When the image is downsampled 8 times, Compared with the traditional Shi-Tomsi algorithm and Harris algorithm, the improved Shi-Tomasi algorithm improves the matching accuracy by 7.8% and 4.0%, respectively, which proves the feasibility of the proposed method.