复数轮廓波变换纹理图像检索系统

Texture Image Retrieval System Based on Complex Contourlet Transform

针对基本轮廓波变换纹理图像检索系统检索率低下的问题,提出了一种基于复数轮廓波变换(CCT)的纹理图像检索系统。该系统采用的复数轮廓波变换由双树复小波变换级联临界下采样方向滤波器构成,特征向量采用子带系数的能量和标准偏差连接而成,以Canberra距离为相似度度量标准;比较了基于同样架构的基本轮廓波变换(CT)、无下采样轮廓波变换(NSCT)、半下采样轮廓波变换(CTS)和CCT纹理检索系统的性能。实验结果表明:在特征向量长度、检索时间、所需存储空间基本相同的情况下,基于CCT的检索系统比CT、CTS和NSCT检索系统具有更高的检索率;各种轮廓波变换分解结构尺度数对检索率也有较大的影响。

Aiming at the problem of low retrieval rate of basic contourlet transform texture image retrieval system, a texture image retrieval system based on Complex Contourlet Transform （CCT） was proposed. The contourlet transform used in the system was constructed by dual tree complex wavelet transform followed by critically subsampled directional filter banks, sub-bands energy and standard deviations were cascaded to form feature vectors, and the similarity metric was Canberra distance. The performance of retrieval system was compared including original contourlet transform, non-subsampled contourlet transform, semi-subsampled contourlet transform （CTS） and CCT under the same system structure. Experimental results show that the image retrieval system based on CCT has higher retrieval rate than those of CT, CTS and NSCT with almost same length of feature vectors, retrieval time and memory needed, and decomposition scale number can make significant effects on average retrieval rates.