The Line-based Wavelet Transform and Application in Image Compression
基于行的小波变换及其在图像压缩中的应用

According to the line based wavelet transform algorithm, the column transform is performed progressively, so lower memory is required without affecting the result of wavelet transform and it is suitable for the memory insufficient system very much. In this paper, the improved lifting scheme is used to perform wavelet transform to replace the traditional Mallat method that is used in the original algorithm. The three adder unit is adopted to realize lifting scheme. The in place calculation property of the lifting scheme makes the original data updated directly by the current computation result. So the synchronous buffer and the splitting operation are not necessary any more. At the same time, one three adder unit can be divided into two two adder units so that less memory is required. However, two two adder units need one more multiplication in contrast to one three adder unit. Thus, there is more computation in two two adder units. Furthermore, the three adder uses the same operations for low pass lines and high pass lines while the two adder needs different. This algorithm has been tested and compared with JPEG2000 in items of PSNR and bit rate. Experimental results show that it is memory efficient and excellent in compression performance.