BALANCED ERROR DIFFUSION SYSTEM

A digital halftoning system with balance error diffusion, converts a scanline at a time of an image from a first pixel density to a second pixel density, where the first pixel density is greater than the second pixel density. Quantization errors resulting from the conversion is dispersed to surrounding pixels, in a manner which is more symmetric than standard error diffusion techniques. Initially, errors are dispersed in a conventional manner during a first scanline pass or forward scanline pass of an image. Subsequently, errors are again dispersed during a second scanline pass or backwards scanline pass. The two pass error diffusion technique insures that error propagated throughout the image do not create or form correlated artifacts such as worms in the converted image.