Abstract: For plane on-board image lossless and near-lossless compression, an improved compression algorithm based on the JPEG-LS was given. The algorithm is composed of three parts, decorrelation processor, adaptive entropy coder and controlling of compression ratio. The new decorrelation model solved the problem of transmission error propagation in JPEG-LS. A fast and effective entropy coder named Golomb was modified and used in the algorithm, and that a valid controlling strategy of compression ratio was present with invariable speed of image data input and output, so a full and feasible scheme was given and simulated with VHDL for airborne image coding and transmission. Furthermore, the whole scheme was implemented and verified with one chip of field-programmable gate arrays(FPGA) manufactured by Xilinx Corp. Results show the encoder meets the application of airborne image coding well in bulk, weight, and power consumption, and all key techniques in FPGA design are referred to.