三维DCT变换编码包括谱段方向的一维DCT变换和由此产生的特征值图像的二维DCT变换编码。谱段方向一维DCT变换的主要作用是去除光谱方向的数据相关性, 并产生由DCT系数构成的并与各个谱段相对应的特征值图像。特征值图像的压缩由JPEG算法完成, 图像的压缩比由JPEG的量化因子q控制。图像边缘特征对高光谱图像的应用具有非常重要的意义, 在高光谱图像的压缩过程中要尽量保持图像的边缘特征。我们设计了具有图像边缘保持特性的量化表, 以取得最佳的量化效果。

The High Resolution Imaging Spectrometer (HIRIS) produces tremendous amounts of raw data. Transmission of these data to a ground receiving station is constrained by downlink communication bandwidth. To alleviate limitation, the data must be compressed. In this paper, we present a compression algorithm for hyperspectral image by using, three dimensional discrete cosine transform coding (3-D DCT). The 3-D DCT includes a 1-D DCT on spectral direction followed by 2-D DCT on the eigen images produced by 1-D DCT. The main effect of the 1-D DCT is to remove the data correlation on the spectral direction, and produces the spectral band corresponded eigen images which are consisted by the DCT coefficients. The resulting spectrally decorrelated eigen images are then compressed using the JPEG algorithm. The compression ratio is controlled by the quantization (Q table) of JPEG. Image edge features are of great significance to the application of hyperspectral image. During the compression, it is pursued to retain the imgae edge feature. We have designed a Q table for retaining the edge feature with maxmum compression.