An image processing apparatus such as a digital printer or digital facsimile apparatus for half tone processing input image data has: an input device to input image data indicative of a concentration of an image; a discriminating circuit to discriminate whether the input image data is smaller than a...http://www.google.com.au/patents/US4975786?utm_source=gb-gplus-sharePatent US4975786 - Image processing method and apparatus with error diffusion capability
