A Fast and Efficient Codec for Multimedia Applications in Wireless Thin-Client Computing

Thin-client computing is uniquely suitable for mobile environments, where resource-poor devices may need to access critical applications over wireless networks. In thin-client computing, applications run on a powerful server, which sends screen updates to the client in real time. However, fast and efficient coding methods for screen updates of multimedia applications are very challenging in wireless environments, for the limited bandwidth and the real-time constraint. In this paper, we present SPEDIC (Simple Predictor and Edge Detector based Image Codec), a fast and efficient codec of continuous-tone images, which is appropriate for multimedia applications in wireless thin-client computing. SPEDIC adopts predictive coding, edge coding and run coding, depending on the characteristics of image blocks, and trades off between compression ratio and coding complexity. The experimental results show that SPEDIC provides good compression ratio with very low coding complexity, especially for continuous-tone images, and achieves the best end-to-end latency over wireless networks. Compared with JPEG-LS, the standard of lossless image compression, SPEDIC compresses 2.5 times faster and decompresses 3.2 times faster than it does for a series of continuous-tone images, and is only 6.2% inferior to it in compression ratio.