Wavelet-based Image Coding Algorithm

With the fast development of computer and communication technology,image encoding is the hot research all along.Although the techniques of data storage are developing and the band of channel is wider than past,the demand for compression for image data is rapidly growing so that to save the space of storage and improve the use ratio of channel.Comparing with lossy image compression,the lossless image compression is more difficult and its development is slower.Now,image compression method based on wavelet is the branch which development is fast in image compressing field.Lifting scheme can design the wavelet transforms that map integer to integer,which provides the effective tool for studying the lossless image compression. On the other hand,the method for wavelet coefficients coding is a key technique to implement image compression,which not only affects the effect of compression,but also the qualities of resuming image and the time of coding and decoding.The old compression algorithm most based on float-DWT,but integer to integer wavelet transform can compress image and video signals losslessly or lossly.In addition,the computation complexity of ITI DWT is below float-DWT.For these reasons,ITI DWT is very useful in image and video coding.And then,in view of the problems of complicated convolution process of wavelet transform,repeated calculations and a large number of needed memories of SPIHT algorithm after wavelet transformation,a new image compression method based on improved SPIHT and integer lifting wavelet transform is proposed.The method improve quality of restructured photo but also combines improved SPIHT.There is the characteristic of economical memory,fast computation and simple encode.The peak SNR for reconstruction image also has some improvement.Experiments demonstrate that it is a viable and effective image compression method.