Abstract: With the frequency warping, the Warped Discrete Cosine Transform（WDCT） makes the signal energy distribution more suitable for image coding. In order to improve the coding performance in the low bit-rate, this paper presents a code frame based on down sampling and All Phase DCT（APDCT） interposition. Experimental results show that, no matter for PSNR or subjective result, the proposed method obviously improves the performance of image coding in low bit-rate, and reduces the block effects significantly.

Key words: Warped Discrete Cosine Transform（WDCT）, low bit-rate, down sampling, All Phase DCT（APDCT）

摘要： 卷曲离散余弦变换（WDCT）通过频率卷曲使变换后的信号能量分布更适合于图像压缩编码。为了提高低比特率图像压缩编码性能，在WDCT中引入基于下采样和全相位延拓DCT内插编码框架。实验结果表明，不论是峰值信噪比还是主观效果，提出的基于下采样和全相位DCT内插的WDCT-JPEG算法在低比特率下编码性能显著提高，方块效应明显减少。

关键词: 卷曲离散余弦变换, 低比特率, 下采样, 全相位DCT内插