Selected Based On Visual Characteristics Of Image Compression Pretreatment

As far as image transmission is concerned many large-scale files including image data will be produced in the digital image processing. Furthermore these data are often exchanged among different users and systems. Large image information bring much compressive stress to capacity of memorizer, channel bandwidth of communications trunk and processing speed of the computer. It is not practical to improve hardware performance merely. Here we take image compression into account.Usually a mass of static image transmitted in narrowband channel need not greatly clear-cut but legible to HVS (human visual system). Thus we choose image processing of large compression rate.The problem is image quality not good enough to satisfy with HVS in processing of large compression rate. So we add a step before image compression, pretreatment. This paper present a pretreatment method of narrowband image transport based on HVS. That is to say, we choose different pretreatment according to different compression format with visual covering effect. The sensitive image part of HVS that will greatly distort is be enhanced to reduce the losing information in image compression. Consequently the pretreatment method realizes enhancement of the compression ratio and improvement of image quality to a great extent so that to clear up the conflict between large compression and greatly digressive image quality.If reasonably choose the pretreatment method to make enhancement processing to original image before wavelet compression, we can effectively restrain the insensitive image part of HVS, increase the proportion of sensitive information to the whole image, and reduce the losing of coefficient quantification in wavelet transform so that the PSNR value of resumed image keeps relatively high level in decoder. More importantly, if reasonably choose the corresponding pretreatment method based on need of different image compression formats, we can improve visual quality with the same compression ratio or enhance compression ratio with similar image quality.