复数轮廓变换在图像编码中的应用

以Contourlet变换为基础，WBCT（Wavelet-Based Contourlet Transform）的思想为依据，提出了一种新的、改进Contourlet的变换－复数轮廓变换CCT（Complex Contourlet Transform）。DT-CWT（Dual-Tree Complex Wavelet）复数小波因为具有近似的位移不变性以及方向可选择性，已经成功地应用于图像压缩领域，然而无法解决小波变换方向选择性差的固有缺点。为了能够得到更多的图像方向信息，将DFB（Directional Filter Bank）方向滤波器引入DT-CWT，从而构建CCT（Complex Contourlet Transform）复数轮廓变换。实验结果表明，和WCBT相比较，CCT变换重构得到的实验图像纹理更加清晰、丰富，视觉效果更好。

Image compression using complex contourlet transform

Dual-Tree Complex Wavelet(DT-CWT) has been thoroughly investigated for image compression,since it takes advantages of direction selectivity.But it can only handle limited direction information.To allow a more flexible directional expansion for images,we propose a new compression scheme,referred to as complex contourlet transform(CCT).It successfully incorporates directional filter banks(DFB) into DT-CWT.As a result it efficiently deals with images containing contours and textures,whereas it retains the property of shift invariance.Experimental results demonstrat that the method features high quality compression performance and can facilitate many image processing applications.