中文摘要：

提出一种新的基于提升Directionlet变换的图像压缩算法,能有效捕捉图像中的多方向各向异性特征,并具备格形可分离的滤波和采样结构.利用四叉树分块寻找局部最优的变换方向,针对Directionlet变换系数分布构造了块集合分裂嵌入编码,并通过改进链表排序方式和设计新的上下文算术编码器,进一步提高压缩性能.仿真实验结果表明,与基于原始Directionlet变换的压缩算法和基于小波变换的SPECK,SPIHT,JPEG2000等经典算法相比,本文算法在性能参数和视觉效果方面均有较大提高,且在低比特率下仍能较完整地保留图像中的边缘和细节信息.

英文摘要：

A new image compression algorithm based on lifting directionlet transform （LDT） is proposed.This transform captures the multi-directional anisotropic image features effciently and processes the structure of lattice-based separable filtering and sampling.The quad-tree segmentation is designed for direction optimization of local region,and a setpartitioned embedded block algorithm for the statistic distribution property of transform coeficients is adopted.The coding performance is improved by designing the new chained list sorting and context-based arithmetic coder.The experimental results show that our proposed compression algorithm outperforms the standard wavelet-based SPECK,SPIHT,JPEG2000 and original directionlet-based methods both in terms of peak signal to noise ratio （PSNR） and visual quality.Especially at the low-rate,our algorithm can preserve better the detailed information.