结合同态滤波与直方图均衡化的井下图像匹配算法

Underground image matching algorithm combining homomorphic filtering and histogram equalizatio

  • 摘要: 针对现有井下图像匹配算法特征点提取不准确、匹配效果不佳的问题,提出了一种结合同态滤波与直方图均衡化的井下图像匹配算法。通过同态滤波对图像进行锐化,以提高图像清晰度;采用限制对比度的自适应直方图均衡化(CLAHE)算法对图像进行处理,以突出图像的边缘细节信息,提高图像对比度。针对传统AKAZE算法存在误匹配的问题,在采用暴力匹配算法进行粗匹配的基础上,采用基于单应性矩阵的随机采样一致性(RANSAC)算法进行精准匹配,剔除错误匹配点对。实验结果表明:使用单参数同态滤波和CLAHE算法对图像进行增强,可拉伸图像的灰度级,减少暗像元数量,增加亮像元数量,使得灰度级分布更加平滑,有利于保留图像的细节和边界信息;采用基于单应性矩阵的RANSAC算法进行精准匹配,可检测出更多特征点,提高匹配准确率,准确率最高可达9609%,匹配效果优于SURF算法和传统AKAZE算法。

     

    Abstract: In order to solve the problem of inaccurate feature point extraction and poor matching effect of existing underground image matching algorithms, an underground image matching algorithm combining homomorphic filtering and histogram equalization is proposed. The image is sharpened by homomorphic filtering to improve the image clarity, and the image is processed by the contrast-limited adaptive histogram equalization (CLAHE) algorithm to highlight the edge detail information of the image and improve the image contrast. In order to solve the problem of mis-matching in the traditional AKAZE algorithm, on the basis of rough matching by the brute force matching algorithm, the random sampling consensus (RANSAC) algorithm based on the homography matrix is used to perform accurate matching and eliminate the mis-matched point pairs. The experimental results show that using single-parameter homomorphic filtering and CLAHE algorithm to enhance the image can stretch the gray level of the image, reduce the number of dark pixels and increase the number of bright pixels, which makes the gray level distribution smoother and helps to preserve the details and boundary information of the image. Using RANSAC algorithm based on the homography matrix for accurate matching can detect more feature points and improve the matching accuracy. The matching effect is better than that of SURF algorithm and traditional AKAZE algorithm with a maximum of 96.09%.

     

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