Hu的七个不变矩在图像匹配检索中适用广泛。本代码仅计算图像间Hu的七个矩的D2大小，直观的了解Hu矩的应用-seven moment invariants in image retrieval in the application of broad match. Only the calculation of the code between the image of the seven Hu moments D2 size, intuitive understanding of the app