Christophe Emmanuel, Mailhes Corinne, Duhamel Pierre
CNES (French Space Agency), Toulouse, France.
IEEE Trans Image Process. 2008 Dec;17(12):2334-46. doi: 10.1109/TIP.2008.2005824.
Hyperspectral images present some specific characteristics that should be used by an efficient compression system. In compression, wavelets have shown a good adaptability to a wide range of data, while being of reasonable complexity. Some wavelet-based compression algorithms have been successfully used for some hyperspectral space missions. This paper focuses on the optimization of a full wavelet compression system for hyperspectral images. Each step of the compression algorithm is studied and optimized. First, an algorithm to find the optimal 3-D wavelet decomposition in a rate-distortion sense is defined. Then, it is shown that a specific fixed decomposition has almost the same performance, while being more useful in terms of complexity issues. It is shown that this decomposition significantly improves the classical isotropic decomposition. One of the most useful properties of this fixed decomposition is that it allows the use of zero tree algorithms. Various tree structures, creating a relationship between coefficients, are compared. Two efficient compression methods based on zerotree coding (EZW and SPIHT) are adapted on this near-optimal decomposition with the best tree structure found. Performances are compared with the adaptation of JPEG 2000 for hyperspectral images on six different areas presenting different statistical properties.
高光谱图像呈现出一些特定特征，高效的压缩系统应利用这些特征。在压缩方面，小波已显示出对广泛数据具有良好的适应性，同时其复杂度也较为合理。一些基于小波的压缩算法已成功应用于某些高光谱空间任务。本文着重于高光谱图像全小波压缩系统的优化。对压缩算法的每一步骤进行了研究和优化。首先，定义了一种在率失真意义下寻找最优三维小波分解的算法。然后表明，一种特定的固定分解具有几乎相同的性能，同时在复杂度问题方面更具实用性。结果表明，这种分解显著改进了经典的各向同性分解。这种固定分解最有用的特性之一是它允许使用零树算法。比较了各种在系数之间建立关系的树结构。基于零树编码的两种高效压缩方法（EZW和SPIHT）在具有最佳树结构的这种近似最优分解上进行了适配。在呈现不同统计特性的六个不同区域，将性能与高光谱图像的JPEG 2000适配情况进行了比较。
