Dot Gain - Controlling Dot Gain

Controlling Dot Gain

Not all halftone dots show the same amount of gain. The area of greatest gain is in midtones (40-60%); above this, as the dots contact one another, the perimeter available for dot gain is reduced. Dot gain becomes more noticeable with finer screen ruling, and is one of the factors affecting the choice of screen.

Dot gain can be measured using a densitometer and color bars in absolute percentages. Dot gain is usually measured with 40% and 80% tones as reference values. A common value for dot gain is around 23% in the 40% tone for a 150 lpi screen and coated paper. Thus a dot gain of 19% means that a tint area of 40% will result in a 59% tone in the actual print.

Modern prepress software usually includes utility to achieve the desired dot gain values using special compensation curves for each machine.