Dot gain

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Dot gain is a phenomenon in printing and graphic arts whereby printed dots are perceived and actually printed bigger than intended. This causes a darkening of the screened images or textures, especially in the mid tones and shadows.

This happens because of the viscosity of ink and its ability to spread through the paper as it is soaked in. Dot gain varies with paper type. Uncoated paper stock like newsprint paper shows the most dot gain.

[edit] Optical dot gain

Optical dot gain, also known as the Yule-Nielsen effect, is a type of dot gain caused by absorption and scattering of visible light by substrate. Light becomes diffused around dots, darkening the apparent tone. As a result, dots appear to be larger than their real physical size would suggest.

The area of the dot may be computed using the Yule-Nielsen model. This requires the optical densities of the substrate, the solid-covered area, and the halftone tint, as well as the value of the Yule-Nielsen parameter, n. Pearson [TAGA Proceedings, 1981] has suggested a value of 1.7 be used in absence of more specific information.

[edit] External link

• Understanding Yule-Nielsen Factors