Sequential Imagery Lossless Compression Algorithm for Space Astronomical Observation

In astronomical observation missions, a large number of sequential imagery is obtained. They are produced by fixpoint photography in a period of time, and all have some common features with high resolution and high time-space redundancy. The large volume of such imagery challenges on-board transmission and storage mission. Hence, an algorithm based on inter-frame prediction is proposed in order to reduce the images' bitrates. It includes the intra-frame compression algorithm and an improved inter-frame compression algorithm. The JPEG-LS is adopted to encoding the first image as the intra-frame compression algorithm. Then the other images are compressed by the inter-frame compression algorithm. First, the next image is predicted by its previous image, and then the prediction residuals are transmitted to JPEG-LS predictor for refining. Finally, the refined residuals are encoded by arithmetic encoder. Arithmetic coding does not require encoding each pixel like Huffman coding, and it is closer to the entropy of the image. The experiment result proves that the proposed algorithm promotes the compression performance, and it has lower complexity and less compression time comparing with the traditional JPEG-LS. The proposed algorithm is suitable for real-time onboard compression of astronomical observation sequential imagery.