The DjVu Reference Library does not contain the entire implementation of the DjVu system. While it contains the entire decoder, and a big piece of the encoder, it does not contain the sophisticated encoding strategies necessary for reaching the highest compression ratios. Among other things, The DjVu Reference Library contains the full DjVu decoder, the full IW44 wavelet encoder/decoder for continuous tone images, and the back-end of JB2 bilevel image compression technique. However, it does not contain the code for separating document images into foreground and background layers, nor does it contain the code of the lossy JB2 scheme that achieves the highest compression ratios on bitonal images. WWW: http://www.djvuzone.org/