二代小波在MPEG-4任意形状图象变换编码中的应用

MPEG-4 Arbitrarily Shaped Image Coding Based on Lift Scheme

本文研究了二代小波在MPEG-4任意形状图象（即VOP）变换编码中的应用。与一代小波相比，二代小波具有能对任意尺寸图象变换的能力，以及压缩与解码算法相似、计算效率高等特点。文中采用了两种方法：一种是对VOP做适当的延拓再进行变换；一种则是在修改提升算法的基础上，获得一种无须延拓的形状自适应变换方法。实验结果表明，与一代小波相比，基于二代小波的形状自适应变换方法在MPEG-4任意形状图象变换编码中具有更好的压缩性能。

The application of second generation wavelet in MPEG-4 coding for arbitrarily shaped images is presented. Compared with traditional wavelet transform，second generation wavelet has a lot of merits: transforming for arbitrarily shaped image without extension; similar decoding and coding algorithms; higher computational efficiency. Two methods are adopted here: one is transforming VOP after appropriately extend; the other is shaped-adaptive transform without extension based on modified lift method. Experiment result shows shaped-adaptive transform method based on lift scheme has better performance compared with the traditional wavelet transform.