We examined the processing of making to binary technique that used edge information in the image. The edge information is calculated in each block that divides the image into the unit of the square of several pixels and the edge information is calculated by the method of comparing mean values of the block with the value of each pixel. Even if the brightness of the screen changes, the edge information can accurately extract the density change. As a result, it has been understood to be able to put out a feature big as the processing of making to binary of the s hading image can be accurately done.