A Novel Method For Remote-sensing Image Compression

With the development of the remote-sensing technique for satellite, the rising of the need for the quality of the remote-sensing images and the heighten resolution ratio of the space-remote images, the memory size and transport layer for the data increase rapidly. For the satellite channel bandwidth limited, we have to carry highly efficient data compression to transmit images effectively. Meanwhile, low Signal-Noise-Ratio due to transmission stream may be wrong, so the important feature for the algorithm is that measures must be taken to prevent the error propagation as early as possible。According to above, a tree-block data lossless compression algorithm with lower complexity is proposed suitable for easier hardware implementation and with good ability for deducing the error propagation(the error propagation is limited within a tree-block).The algorithm uses wavelet-based bit plane coding. First, coefficients at all levels filtered by discrete wavelet transform are sorted in accordance with the structure of the tree, and a number of trees that they are neighboring constitutes a tree collection, called tree-block; the statistical regularity of every tree-block coefficients filtered by discrete wavelet transform is different, to effectively compress the image data, the standard adopts different entropy codes according to different statistical regularity; in order to minimize the output bit-rate, the adaptive optimization to select corresponding codes is discussed, including the choice of the parameter k for the DC quantization and block AC bit-depth coding, and decision of the entropy coding length of 3-bit code word encoding parameters choicel and choice3 as well as the length of 4-bit code word encoding parameters choice2 and choice4;every tree-block is encoded independently, and the stream is also packaged independently. The experiment results show that the algorithm is lower in complexity and convenient for hardware implementation, and has good error feature.The ratio can be optimized, the resulting a minimum output bit ratio can be arrived.