Research On JPEG XR Encoder And Implementation By FPGA

JPEG XR standard is the next generation of still image compression standard, the prototype comes from Microsoft's HD Photo standard. Because of the use of advanced image compression technology, JPEG XR standard can provide a simple algorithm for higher compression performance. Compared with the JPEG standard, JPEG XR standard which overcomes the problem of block effect in low bit rate can provide better image quality and its file size is reduced by half; and JPEG XR standard uses optimized algorithm, its computational complexity significantly is higher than that in the JPEG2000 standard, so it is easy for hardware implementation of JPEG XR encoder. Therefore, the research on standard algorithm for JPEG XR standard and implementation by FPGA is of great significance.Firstly, we study the standard algorithm for JPEG XR, mainly study the encoding process which can be divided into color changing, overlapping biorthogonal transform, quantization, prediction coding and adaptive entropy coding module. Then we analyzed the data structure of the encoding process and encoding algorithm of each module the process included the principle of the algorithms and the algorithm flow respectively. Then for each module, respectively, FPGA, VHDL code written for each module, and simulation functionality, including color conversion module, and overlapping modules biorthogonal lines are used to quantify the module implementation.Finally, we design the whole architecture of JPEG XR encoder which can be divided into four pipelines, the first-stage pipeline includes color transform module and the pre-filter module, the second-stage pipeline includes the prior core transformation module and the quantification module, and the third Stage pipeline contains predictive coding module, the fourth-stage pipeline includes adaptive entropy coding module, through simulation, under the control of the pipeline, JPEG XR encoder's coding rate can reach 0.397 pixel/clock cycle, and can achieve the high-speed compression for the image with the size about 512×512 at the speed of 75.8 frame/second at the clock frequency about 50MHz and the compressed image can be completed by the normal decoding Display.