Hewlett-Packard Co., Palo Alto, CA.
IEEE Trans Image Process. 1995;4(3):296-308. doi: 10.1109/83.366478.
Multispectral images are composed of a series of images at differing optical wavelengths. Since these images can be quite large, they invite efficient source coding schemes for reducing storage and transmission requirements. Because multispectral images include a third (spectral) dimension with nonstationary behavior, these multilayer data sets require specialized coding techniques. The authors develop both a theory and specific methods for performing optimal transform coding of multispectral images. The theory is based on the assumption that a multispectral image may be modeled as a set of jointly stationary Gaussian random processes. Therefore, the methods may be applied to any multilayer data set which meets this assumption. Although the authors do not assume the autocorrelation has a separable form, they show that the optimal transform for coding has a partially separable structure. In particular, they prove that a coding scheme consisting of a frequency transform within each layer followed by a separate KL transform across the layers at each spatial frequency is asymptotically optimal as the block size becomes large. Two simplifications of this method are also shown to be asymptotically optimal if the data can be assumed to satisfy additional constraints. The proposed coding techniques are then implemented using subband filtering methods, and the various algorithms are tested on multispectral images to determine their relative performance characteristics.
多光谱图像由一系列在不同光波长下的图像组成。由于这些图像可能非常大，因此需要有效的源编码方案来降低存储和传输需求。由于多光谱图像包含具有非平稳行为的第三（光谱）维，因此这些多层数据集需要专门的编码技术。作者为多光谱图像的最佳变换编码开发了理论和具体方法。该理论基于这样的假设，即多光谱图像可以建模为一组联合平稳高斯随机过程。因此，这些方法可以应用于满足此假设的任何多层数据集。尽管作者不假设自相关具有可分离的形式，但他们表明，用于编码的最优变换具有部分可分离的结构。特别是，他们证明了在块大小变大时，由每层内的频率变换 followed 以每个空间频率跨层的单独 KL 变换组成的编码方案是渐近最优的。如果可以假设数据满足其他约束，则还证明了该方法的两种简化形式是渐近最优的。然后使用子带滤波方法实现所提出的编码技术，并在多光谱图像上测试各种算法，以确定它们的相对性能特征。
