Huffman Coding of Wavelet Lower Trees for Very Fast Image Compression

In this paper, a very fast variation of the lower-tree wavelet (LTW) image encoder is presented. LTW is a fast non-embedded encoder with state-of-the-art compression efficiency, which employs a tree structure as a fast method of coding coefficients, being faster than other encoders like SPIHT or JPEG 2000. The alternative Huffman-based encoder presented in this paper serves to largely reduce the execution time, at the expense of loss in coding efficiency. Experimental results show that this encoder is more efficient than other very fast wavelet encoders, like the recently proposed PROGRESS (which is surpassed in up to 0.5 dB), and faster than them (from 4 to 9 times in coding). Compared with the JPEG 2000 reference software, the encoder is from 18 to 38 times faster, while PSNR is similar at low bit-rates, and about 0.5 lower at high bit-rates