dithering
1. Simulating a gray scale by using a group of pixels each capable of displaying only black and white.
2. A technique for varying raster color or intensity by illuminating and blanking pixels in patterns to produce a blurred transition from one color to another in a computer picture.
Note: Dithering is used to create a wide variety of patterns for use as backgrounds, fills and shadings, as well as for creating halftones, and for correcting aliasing. [ANSDIT]