Dispersion-based technique for performing spacial dithering for a

Abstract

A technique for performing spacial dithering for a digital display system. A display panel is portioned into eight-by-eight arrays of 64 pixels, each pixel including three primary color sub-pixels. A predetermined number of bits represent a color level for each sub-pixel according to image data. If the display system can accept only fewer bits than the predetermined number, bits must be discarded. The discarded bits are used to modify the remaining bits before the remaining bits are passed to the display system. A memory stores 64 tables, each table including an entry for each pixel within an eight-by-eight array. The entry for a pixel determines whether or not the color level for the corresponding sub-pixel is to be decremented by one. A first of the sixty-four tables does not result in decrementing any color levels. Each successive table decrements the color level for one more pixel than the previous table. The values of discarded bits select among the stored tables. whereas, the values of bits that are retained are selectively decremented according to entries in the selected table. Entries in the tables are dispersed so as to avoid decrementing color levels in a pattern that would otherwise tend to result in image artifacts. This is accomplished by avoiding vertical, horizontal or diagonal lines, and checker-board patterns of pixels for which the color level is decremented. As a result, artifacts induced by the dithering process are reduced in comparison to prior dithering techniques.