UH-JLS: A Parallel Ultra-High Throughput JPEG-LS Encoding Architecture for Lossless Image Compression

The lossless image compression technique has a great application value in distortion-sensitive applications. JPEG-LS, as a mature lossless compression standard, is widely adopted for its excellent compression ratio. Many hardware JPEG-LS compressors are proposed on FPGAs and ASICs to achieve high energy efficiency and low cost. However, JPEG-LS has a contextual Read-After-Write (RAW) issue, making previous hardware either insufficiently explore its parallelism potential or induce other defects while parallelizing, such as compression ratio dropping and compatibility problems. In this paper, we propose a hardware/software co-design method for high-performance JPEG-LS compressor design. At the software level, we propose a pixel grouping scheduling scheme and the Pseudo-LS method to tap the parallelism aiming at the RAW issue. At the hardware level, we discuss the high-performance design methods of these software-level schemes and propose a design space exploration method to constrain the resource usage introduced by parallelization. To our knowledge, our architecture, UH-JLS, is the first pixel-level parallelization streaming image compressor based on the standard JPEG-LS. The experiments show that in the lossless manner and the Pseudo-LS manner, UH-JLS respectively achieves 5.6x and 7.1x speedup than the previous state-of-the-art FPGA-based JPEG-LS compressor.