Half-tone Technology Study Of Image Based On Error Diffusion

Digital half tone technology is the bridge of connecting digital change and printer of simulated manuscript or physical scene and is the key tech of digital print or modern print.Nowadays this technology is widely used to some areas which is closely related with people's life such as digital water print,the information encryption,picture compression,picture transportation,medical image processing and so on.All of those areas are closely related with people's daily life,which makes digital half tone technology plays an extremely important role in modern area of image processing and has extremely important pragmatic meaning in the field of output of hardware copy and display.However,as the key branch of technology of digital half tone,the half tone algorithm of error diffusion has very important value of research.The main content of this text are as following:First,the current scanning way of half tone algorithm of error diffusion include raster scanning style,snake scanning style and space filled curve.The output image of raster scanning error diffusion has obvious worm phenomenon in the high light and dark light gray level.Besides the medium frequency spectrum has some structure texture.As for the halftone algorithm of error diffusion using filled curve,it will bring some extra noise to the half tone image,so the quality of halftone image is also not so good.As for these reasons above,a new halftone algorithm of error diffusion which is based on disconnected scanning way is proposed.At the same time,the solid threshold is changed to adaptive threshold when the pixel is changed to binary.In the way of interval scanning,we will choose an appropriate error diffusion filter according to the gray level of current pixel.Compare with snake scan and raster scan,Interval scanning style can make the quantization error spread in two direction of right and left when dealing with the same line pixel points which relieves formation of phenomenon of worm and improves the quality of half tone image.Second,a new half tone algorithm which is based on improved errordiffusion filter and a new evaluation method of half tone image based on average gray and contrast are proposed.Compared with traditional error diffusion filter,improved error diffusion filter can make the quantization error spread widely,prevent the worm links from forming effectively and has no extra noise in the result picture.At the same time,the computation complexity has no extra increase.