11.3.1.4.1-8 Moiré Patterns

The screen image should be free of Moiré patterns when observed over the range of anticipated viewing distances and angles.

Additional Information: Moiré patterns are unwanted periodic patterns in or around the intended image on the screen. They can appear as ripples, waves, and intensity variations that are superimposed on the screen image. Such periodic patterns are easily noticed by observers and tend to mask the displayed information. Moiré patterns can occur when the image represented contains spatial frequencies with periods less than twice the distance between adjacent pixels. In an approximation, the contrast of the fundamental spatial frequency of such patterns should be a maximum of 0.07 over the range of spatial frequencies from 0.5 to 7 cycles per degree of visual angle, where contrast = (Lmax—Lmin) /

(Lmax + Lmin), for the luminances (L) of the Moiré pattern. The maximum allowable contrast then rises approximately linearly from a value of 0.07 to a value of about 1.0 over the range of spatial frequencies from 7 to 12 cycles per degree of visual angle. The cited reference gives a more precise relationship between maximum contrast and spatial frequency. See IDMS (2012) for measurement information. 10 100,

9241-303

© ISO. This material is excerpted from ISO 9241-303: 2011 with permission of ANSI on behalf of ISO. All rights reserved.