Determine color separation parameters based on paper properties

First, the offset point is increasing

When the ink is transferred to the surface of the paper under pressure, due to the absorption of the paper, the ink spreads around when it penetrates, resulting in an increase in dots and making the entire image darker. Obviously, different dot gains will occur for different quality papers. The stronger the paper absorbency, the larger the dot gain value. Specifically, newsprint is the largest and coated paper is the smallest. The enlargement of the dot formed by the paper performance generally presents an expansive law of enlargement. In the prepress processing process, it is necessary to compensate for the effect of dot gain.

The dot gain value is different for different sizes of dots. Generally, the value of the high-profile and dark-tone network increase is small, and the halftone dot gain value is larger. It is generally recommended that the default settings be better. For example, the default value is 17% for coated paper, about 22% for offset paper, and about 30% for newsprint.

Second, select color separation type GCR, UCR

With GCR, it is easy to maintain the gray balance, reduce the total amount of ink overprint, make the ink dry faster, and increase the printing speed. The quality of the black edition plays a decisive role in the entire printing. For general manuscripts, GCR is recommended. Special manuscripts, such as high school tune-rich, shadow-rich images, can also use UCR. In short, be flexible.

Third, the total amount of ink set

The printing properties of paper, as well as the high speed of rotary printing, determine that the total amount of ink cannot be too high. Foreign data shows that: the total blackness of newsprint printing is generally controlled at 240% to 260%; the total ink volume for coated paper printing is generally controlled at 280% to 320%; the total ink volume for offset printing is generally controlled at 300% to 340%. The setting of this value is determined by each process and completely depends on the dot gain rate at the time of printing.

If the network expansion is serious, the value must be reduced. Otherwise, the dark tone will be crushed and the level of shadow loss will be serious. If the network expansion is basically normal, the value can be increased to ensure that the dark tone is full and full. Shadowing the level of the region is conducive to the reproduction of the entire tone. In addition, inks that are compatible with different papers should also be selected.