Bit Assignment Optimization for ROI of CCSDS Image CompressionStandards Based on DWT

摘要

In deep space exploration, image compression plays an important role in maximizing returned scientific data. CCSDS adopts the methods based on Discrete Wavelet Transformation as the image compression standards because of its high compression ratio, progressive transmission and supporting lossless compressing. According to its feature, a new image compression scheme - Region of Interest encoding is presented for balancing the initial image acquiring rate, buffer size and data transmission rate on spacecraft in deep space communication. It is performed by which ROI is assigned with lower compression ratio, more storage space, and higher transmission priority. Thus it could be attained the goal of acquired image in deep space communication-maximizing information returning to the ground. And an optimized bit allocation method between ROI and Non-ROI is proposed according to rate-distortion model that is fit for progressive wavelet coding rate and distortion. Based on taking 2-level priority as an example, an optimized bit allocation method between ROI and Non-ROI is discussed .Simulation results show that the performance of the scheme is satisfying.