During the last decade, a lot of research and development efforts have been made to design competitive still image coders for several kinds of applications. We present a new wavelet still-image coder, called LTW (lower-tree wavelet), based on the construction and codification of coefficient trees, as other proposals are. This algorithm is fast and symmetric (except at 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 (0.8 dB PSNR) and stack-run (0.13 dB) coders. Also, we have tested the temporal complexity of the LTW algorithm, resulting in it being 3.5 times faster than an optimized EZW (embedded zero-tree wavelet) encoder.
['José Oliver', 'Manuel P. Malumbres']
A new fast lower-tree wavelet image encoder