A Wavelet - based Image Codec for Interactive Network Applications

—Multimedia network systems require image and video compression schemes in order to efficiently take profit from the available bandwidth. In this paper, we present a wavelet still-image coder, called LTW (Lower-Tree Wavelet), based on the construction and codification of coefficient trees as other proposals do. This algorithm is fast and symmetric (except in extremely low bit rates), which makes it adequate for real-time interactive multimedia applications. We have compared our algorithm with several well-known coders in terms of rate/distortion performance using the standard Lena image. Results show that LTW, with lower temporal complexity, achieves better results than EZW (0.9 dB PSNR) and stack-run (0.25 dB). Also, we have tested the temporal complexity of LTW algorithm, resulting 3.5 times faster than an optimized EZW. On the other hand, compared to DCT-based standards, like J PEG, our algorithm outperforms them in 5 dB approx. (at similar bit rates)