为了提高离散余弦变换(dCT)在视频图像编码中的效率,根据dCT对非水平/非垂直残差信号较敏感的特点,从改变残差信号分布的角度出发,提出一种重排dCT方法.对待编码的残差图像块进行像素位置重排,使得残差信号的方向与水平或垂直方向相一致;对重排后的图像块进行2维dCT,从而减少dCT系数的高频分量,提高压缩效率.实验结果表明:在不考虑重排信息的情况下,重排dCT比传统dCT性能提高0.20~0.30db;在考虑重排信息的情况下,重排dCT比传统dCT性能提高0.05~0.20db.In traditional video compression,discrete cosine transform (DCT) is sensitive to the prediction error with non-horizontal or non-vertical orientations.To improve the performance of DCT in video compression,this work proposed a reorder DCT method,from the view point of modifying signal distribution.In the algorithm,reorder operation was first used to change the pixel position of the blocks to be transformed,and then 2D-DCT was applied.Experimental results show that the reorder DCT can reduce the number of DCT coefficients at high frequency.Compared to the traditional DCT,the reorder DCT achieved 0.20-0.30 dB peak signal-to-noise ratio (PSNR) gain without reorder information.With reorder information,0.05-0.20 dB PSNR gain could be obtained.福建省科技厅重大专项资助项目(2007HZ0003
