Human Systems Integration Division @ NASA Ames

The problem of representing gray-level images on a binary display device is known as "dithering" or "halftoning." (A good survey can be found in Ulichney1 ). Dithering relies upon the fact that the human visual system integrates information over spatial regions, so that a spatial pattern of light and dark can evoke a sensation approximating that of a uniform gray area even when the individual display elements can be resolved. Electronic image display devices, such as cathode ray tubes and flat panel displays offer the additional possibility of exploiting the visual system�s integration in the time domain to increase a display�s gray scale resolution; additionally, it may be possible to exploit the visual system�s spatiotemporal sensitivity to make dynamic dithering noise which is less visible than the corresponding static noise. In this paper we examine how a number of existing two-dimensional dithering methods may be generalized to three dimensions.