Halftoning/Screen Angle

Halftoning is what gives the eye perception of more colors when printing. Without halftoning the three primary process colors would be printed only as solid blocks of color, which would only allow us to produce seven colors total: the three primaries, plus three secondary colors produced by layering two of the primaries: cyan and yellow produce green, yellow and magenta produce red, cyan and magenta produce a purplish blue, finally you can layer all three of them producing a black. Halftoning allows for less than full saturation of the primary colors. There are tiny dots of each primary color that are small enough so the human eye perceive a solid color. Magenta printed at a 20% halftone will create a pink color because the eye picks up the tiny dots of magenta on the large white paper and this creates a lighter, less saturated color then just pure magenta would.

Moiré patterns can be created when printing is done with the wrong screen angle, each color has a different screen angle. The angle used depends on each color independently and the choice of the press operator. You will see typical CMYK printing used in any of the below screen angles.

C-15°-15°-105°-165°

M-75°-45°-75°-45°

Y-0°-0°-90°-90°

K-45-°75°-15°-105°