Recovering added precision from l-bit samples by dithering the samples prior to an averaging computation

Abstract

A dithering system comprising a dithering unit, a storage medium, and an averaging unit. The dithering unit is configured to receive a set of data values, to add dither values to the data values, and to truncate the resultant addition values to L-bit truncated values. The storage medium is configured to store the L-bit truncated values. The averaging unit is configured to read the L-bit truncated values from the storage medium, and to compute an average value using at least a subset of the L-bit truncated values. The dither values may have an average value of approximately one-half. The dither values may approximate a uniform distribution of numbers between −A+½ and A+½, wherein A is greater than or equal to one. Alternatively, the dithering unit may receive a temporal stream of data values, and the average unit may perform a temporal average (e.g. an FIR filter). The dithering system may be incorporated in a graphics system. In this case, data values may represent rendered sample values (e.g. color or alpha).