Halftone Dot Evolution

The conventional halftone dot was invented the late 1800’s and has remained virtually unchanged ever since - a solid geometric object designed to carry ink. Concentric Screening™ is a revolutionary halftone screening technology in which the solid geometric object, or halftone dot, is divided into thin “concentric” rings. The thin rings limit ink film thickness on the offset plate. The result is a halftone dot which exhibits higher color saturation, prints with less variation, and enables the use of much higher screen rulings than conventional dots. Concentric Screens have been shown to be superior in printability and visual appearance to both conventional screens and even the latest stochastic screens.

The function of the Concentric Screen is to provide the benefits of stochastic without the grainy appearance. A stochastic screen is a small spot which is randomly distributed. The benefits of stochastic screening are related to the small spot size - not the random distribution. Small spots limit ink film thickness on the offset plate. Large spots, as are found in traditional screens, have no ink limiting property. When enough ink is applied to the plate to print an acceptable solid, large dots carry all of the ink. The thick ink film resulst in reduced chroma. When natural variation causes the amount of ink applied to the plate to change, large dots carry a varying amount of ink. The result is color variation.

Like small stochastic spots, thin concentric rings carry a limited capacity of ink. This capacity is reached at a level far below that required to print an acceptable solid. The result is a cleaner appearance with higher chroma. When natural press variation causes the amount of ink applied to the plate to change, the thin rings continue to carry the same amount of ink. The result is reduced color variation and less waste.

What Is Concentric Screening?

Concentric Screening™ is like traditional screening, but the round dots are divided into thin concentric rings. The purpose of Concentric in offset printing is to achieve the benefits of a stochastic dot with the smoothness of a traditional.

Stochastic screens contain small spots which are randomly distributed. The benefits of stochastic are related to the small spot size, not the random distribution. While the small spots of stochastic limit ink film thickness on the offset plate, the random distribution can cause a grainy appearance.

By dividing the traditional dot into thin concentric rings, similar - even superior - ink limiting characteristics are achieved. The result is a dramatic increase in quality and stability - resulting in higher chroma, cleaner printing, and the ability to print higher screen rulings.