Highly efficient zerotree wavelet image Coder with reduced symbols

This paper presents a novel wavelet compression technique to increase compression of images. Based on extension of zerotree entropy coding method, this method initially uses only two symbols (significant & zerotree) to compress image data for each level. Additionally, sign bit is used for newly significant coefficients to indicate them being positive or negative. Contrary to isolated-zero symbols used in conventional zerotree algorithms, the proposed algorithm changes them to significant coefficients and saves its location, they are then treated just like other significant coefficients. This is done to decrease number of symbols and hence decrease number of bits to represent the symbols used. In the end, algorithm indicates isolated-zero coordinates that are used to change the value back to original during reconstruction. Noticeably high compression ratio is achieved with no change in image quality.