A Novel Method For Image Lossy Compression Convenient For Hardware Implementation

With the rapid development of modern space technology, Remote-sensing images have been widely used in environmental monitoring,satellite images,military reconnaissance,geological exploration etc. The use of high resolution communications satellites makes the amount of data transported from the space station to the ground station is growing. In order to reduce and buffer storage space,reduce the transmission bandwidth,as far as possible to reduce data transmission time in a given condition, we need to carry out the high-effect compression on the original data.Consultative Committee for Space Data Systems(CCSDS for short) has proposed the image data compression standard for space remote sensing image formally in November 2005.The core of this algorithm is wavelet transform and bit plane encoding, owing to its simple structure,low complexity,easy hardware implementation and can achieve real-time processing of spatial data, it can be widely used in space exploration. The main work of this paper is as follows:(1) Learn the basic theory of wavelet transform and make a deep study of wavelet transform in CCSDS image data compression standard. Mainly for image lossy compression algorithm, so I have chosen the 9/7 discrete wavelet transform of the standard.(2) Make a deep study of the algorithm which is proposed in CCSDS image data compression standard.Though segment header encoding,DC coefficient quantization encoding,AC bit depth encoding in block,bit plane encoding, it has make a effectively compression on image. After system simulation to analyze the performance of its compression, it's proved that this algorithm is helpful in improving the quality of reconstructed image.(3) Through selecting the parameters K of DC coefficients quantization coding and AC bit depth encoding and choosing the code method of 3-bit words (choice 1) or 4-bit words (choice2) in entropy coding implement the data progressiveness coding. These code streams have embedded feature, then any code streams can be truncated and decoded, and control the code rate efficiently.(4) Limit of rate distortion optimization has made a further optimization of CCSDS image compression algorithm.