Double color book printing, simply refers to the process of reproducing the effect of a manuscript by using a combination of two different colors of ink. Generally, in the C, M, Y, and K four color plates, the black (K) plate is combined with any other three colors (C, M, Y) plates. The black book printing plate can enhance the contrast of the image tone because of the stronger information distribution of the image order in the dark tune.           

The main points of the design of double color printing           

In the light, the tone of the Black Edition is weakened, and the color levels of C, M and Y are stronger. This can make the level of the image and the color change superimposed together. It is easier to reproduce the original color level and order information of the image. While the combination of C, M and Y Tri Color, although the color range of the bright location is large, but there is no image level in the dark place, which leads to the small color contrast of the image, and it is difficult to reproduce the original effect of the image. Therefore, most of the two color booklet printing designs refer to the combination of black and other spot colors.           

The key to double color book printing is to make double color processing to achieve the desired color effect by changing the relationship of dual color combination on the basis of fully protecting the original level and order information of the image. The best tool to achieve this color effect is the double tone in the Photo - shop image processing software.           

Dual tone is achieved by adjusting two different color curves to achieve graphic designer's image effect. That is to say, dual color printing is not a direct reduction of C, M, Y, and K four colors (minus two channels, two channels), but based on the structure principle of the gray pattern image itself. Adjust the two colors through the curve tool and recombine the colors at different levels.