Aliasing

Aliasing, in computer graphics, the effect produced when display resolution is too coarse to minimize the jagged, or “stairstep”, appearance of certain design elements, such as diagonal lines, curves, and circles. Aliasing occurs because pixels (dots on the screen) are arranged rectangularly, in rows and columns. If this grid is not fine enough, pixels sometimes cannot always be lit in a pattern that the viewer will perceive as a smooth diagonal or curve. Aliasing is clearly visible on low-resolution screens or when a small portion of a graphic is enlarged to display the individual dots that constitute it.

Because aliasing occurs when the resolution of an image is too coarse to achieve the appearance of a smooth line or curve, one approach to anti-aliasing is the use of higher-resolution display modes or hardware. In addition, anti-aliasing software routines can blur the roughness of a jagged line by shading or colouring neighboring pixels to make the transition between light and dark (or between two colours) less distinct and therefore less immediately visible.