DCT Sign Based Correlation and Its Application to Image Matching

DCT（Discrete Cosine Transform，离散余弦变换），特别是在图像压缩中，作为信号转换的一种方法，已经应用于各个领域。在这项研究中，我们集中在DCT系数的符号和傅里叶变换的相位之间的相似性。传统的图像匹配是利用傅里叶变换的相位进行的，提出了一种利用离散余弦变换系数的符号进行图像匹配的新方法。验证了该方法的有效性并对其进行了评价，同时考虑了其可拓性和性能。具体成果如下：(a)推导了DCT系数与相位信息的理论关系，(b)利用DCT系数的符号提出了一种新的相关性，(c)在亚像素精度图像匹配中的应用，(d)在考虑安全性和相位置差的情况下对图像匹配的扩展，(e)对加快图像匹配速度的研究。

DCT(Discrete Cosine Transform, Discrete Cosine Transform), especially in image compression, has been used in various fields as a method of signal conversion. In this study, we focused on similarities between the signs of DCT coefficients and the phases of Fourier transform. The conventional image matching is performed using phases of Fourier transform, a new method of using signs of DCT coefficients is proposed. The effectiveness is confirmed and evaluated, and the extension and performance are considered. Concrete results are as follows.(a) Derivation of the theoretical relationship of DCT coefficients and phase information,(b) Proposal of a new correlation by using the signs of DCT coefficients,(c) Application to Image Matching of sub-pixel accuracy,(d) Extension to image matching considering the security and phase scrambling,(e) Investigation of speeding up image matching.