提出了一种基于提升方向波变换SAR图像的压缩算法.该算法构造了方向波变换的提升方案, 通过改进的四 叉树分块算法寻找局部最优的变换方向, 有效地描述了图像中的方向特征.根据变换系数分布特性构造了多方向 各向异性的多级零树结构, 提高了编码效率.对多幅SAR图像的压缩实验表明, 较之基于小波的SPIHT和 JPEG2000等算法, 本文方法在性能指标和视觉效果方面均得到了明显提高, 尤其在低比特率下, 优势更加突出.

A novel SAR image compression algorithm was presented by using lifting directionlet transform(LDT). The lifting directionlet scheme and improved quad-tree segmentation were proposed to obtain the optimal pair of transform directions, which could capture the image features efficiently. To enhance the coder performance, multi-directional anisotropy hierarchical zerotree was designed, which was suitable to the distribution characteristic of LDT coefficients. Experimental results of real SAR images show that the proposed compression algorithm outperforms the wavelet-based SPIHT and JPEG2000 both in terms of evaluation metric as well as visual quality, especially at the low-bitrate.