The Implementation Of JPEG Image Decoding And LCD Display Based On S3C44B0X

JPEG standard is a mature image coding technology, which is featured with high compress rate, little distortion rate and high run-time speed. And what's more, it is convenient to realize. Adapted as an international standard, it has been applied in many fields. With the development of embedded technology, JPEG image codec technique has been used in many multimedia systems, such as multimedia mobile phone, digital camera, and palmtop high-performance scanner etc. At present, the special ICs are employed to realize JPEG image codec. But its cost is high and it is difficult to upgrade and expand. In this paper, JPEG image codec is realized by employing optimization algorithms based on high-performance ARM processor. It makes the system upgrade and expand easily; it has a higher flexibility, adaptability and lower cost simultaneously.The implementation of JPEG image decoding and display is mainly based on software programming in my scheme, which makes full use of ARM hardware platform. Firstly, A hardware processing platform is constructed on the basis of SAMSUNG's S3C44B0X ARM processor, furthermore, bootloader code, bottom driver and display module program have been developed on this processor, which facilitates the software and hardware for realizing the embedded image processing system. Secondly,according to JPEG standard, decoding programs are designed. The process of decoding consists of five parts:tag code information processing, entropy decoding, inversed quantization, inversed discrete cosine transform and color space converter. As to IDCT which needs a lot of time in the process of decoding, a method named row-column decomposition is adapted, which decompounds the 8*8 two-dimensional into rows and columns with 1-D. then proceeds with fast algorithm of 1-D. The efficiency of IDCT programming could increase greatly. Thirdly, display processing system is developed to perform display on LCD terminal. Finally, the further optimization has been done for the decoding program on the aspects of hardware characteristic of S3C44B0X and C program structure.A lot of tests have been done on the decoding speed and the picture quality. The results show that the program can perform efficiently and is enough to meet the real-time qualification. The quality of reverting pictures is excellent with a higher S/N ratio. It makes the scheme apply to the static image processor easily and widely in the digital cameras, PDA etc. In additional, it has an important reference value to the R&D of M-JPEG, MPEG, MPEG-II, and H.26x.