线性相位余弦调制滤波器组研究

Research on linear phase cosine modulated filter banks

图像子带编码要求滤波器组具有线性相位特性,非线性相位特性可对图像编译码带来影响。现研究了一种具有线性相位的最大抽取FIR余弦调制滤波器组,该滤波器组中每一个滤波器都具有线性相位,且由原型滤波器经余弦序列调制得到。经推导这种滤波器组可以设计成具有近似准确重构(NPR)特性或准确重构(PR)特性,文中分别给出了两种情况下滤波器组应满足的条件。通过对一幅图像的二维可分离滤波实验说明了当原型滤波器满足一定条件时滤波器组是准确重构的。

Linear phase property of filter banks are desired in subband image coding. Nonlinearity leads to some artifacts in the reconstructed image. In this paper we study linear phase maximally decimated FIR cosine modulated filter banks, in which each filter has linear phase and is obtained by modulating the prototype filter by cosine sequences. The system can be designed to have either the nearly reconstruction property or perfect reconstruction property, and the NPR, PR conditions are given respectively. Some simulation results are presented when the PR conditions are satisfied.