Image Compression Algorithm Based On Improved SPIHT

Image as an important information carrier,direct transmission and storage requires very high bandwidth and storage space,so proper compression has important practical significance.Among the many image compression algorithms,wavelet transform image compression can decompose multi-level resolution of the image,and can be embedded coding.It is very consistent with the needs of network transmission.In this paper,the set partitioning in hierarchical trees(SPIHT)algorithm based on wavelet transform is studied,and an improved SPIHT algorithm combined with human visual characteristics is proposed.Firstly,the initialization of the root node in the SPIHT coding scheme is improved.The LIP and LIS are initialized to the nodes with no descendants in the lowest frequency sub band,which solves the problem when the threshold is too large to output too many zero bits.That make you can encode more image information.Secondly,when the LIS list is judged to be important,the four child nodes are treated as a whole,which can reduce the output bits.And a new list is added to save the maximum value of the offspring in the LIS,which reduces the number of searching for the maximum value of the offspring and improves the coding speed.Then,a visual mask scheme based on contrast sensitivity function(CSF)is proposed.The image is weighted by the visual mask after wavelet decomposition,which enhances the visual sensitive information.And the visual effect of the reconstructed image is better.The simulation results show that when the threshold is large,the number of coded bits decreases significantly,and the number of the maximum number of search generations decreases greatly.The PSNR of the improved algorithm is improved by 0.28~1.01 dB at the same bite rate.The MSSIM is raised by 0.05 at low bit rate.And the visual effect of the reconstructed image is better.Finally,the improved SPIHT compression algorithm is applied to region of interest(ROI)coding.The simulation results show that compared with the improved algorithm,the image quality of ROI is improved,and the PSNR is improved by 2.44~4.45 dB.