A method of and system for rendering a halftone image of a gray scale image by utilizing a pixel-by-pixel comparison of the gray scale image against a blue noise mask is disclosed in which the gray scale image is scanned on a pixel-by-pixel basis and compared on a pixel-by-pixel basis to an array of corresponding data points contained in a blue noise mask stored in a PROM or computer memory in order to produce the desired halftoned image. Both digital and optically implemented halftone methods are disclosed. Application specific modifications of the blue noise mask as well as its use for producing halftoned color images are also disclosed.

Method and apparatus for halftone rendering of a gray scale image using a blue noise mask

Method and apparatus for halftone rendering of a gray image using a blue noise mask

Computer-aided geometric design is a subject which involves the representation, specification, design, manipulation, display, and analysis of free-form curves and surfaces. This eclectic field draws on techniques and principles from numerical analysis, approximation theory, computer graphics, interactive computer systems, mechanical and geometric design, and many other areas. Nevertheless, computer-aided geometric design is an endeavor with a character, emphasis, and purpose of its own, combining techniques and principles from other fields with unique approaches that are often somewhat enigmatic and confusing to the novice. Many things sound and seem familiar, yet the directions and motivations are distinct to this discipline. This decade is proving to be an era of intense interest in computer-aided geometric design, an activity attracting people from many sectors including computing and manufacturing. As the discipline more firmly establishes valid principles and standard techniques, it will undoubtedly be of increasing importance in computer-aided manufacturing and a wide range of other applications.

Computer-Aided Geometric Design: A bibliography with Keywords and Classified Index

The limitations of human vision provide the justification for design of systems for printing or display of halftone images that are perceived to be nearly identical to a continuous-tone original. Despite this fact, a review of existing halftone algorithms indicates that only limited use has been made of the extensive research on human vision. This review also emphasizes the common features of the many algorithms that have been proposed. It is suggested that iterative techniques may provide a means of incorporating a much more complete visual model within the halftoning algorithm.© (1981) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Visual Model-Based Algorithms For Halftoning Images

Computer graphics: A keyword-indexed bibliography for the years 1976, 1977, and 1978

It is shown that, when ordered dither is employed, the constrained-average algorithm presented in the above paper is equivalent to ordered-dither coding of a picture which has been subjected to a well-known method of edge enhancement. The magnitude of the parameterγ controls the degree of edge enhancement and the dither signal amplitude controls the picture contrast.

B. Lippel

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