This paper surveys current technology and research in the area of digital color imaging. In order to establish the background and lay down terminology, fundamental concepts of color perception and measurement are first presented using vector-space notation and terminology. Present-day color recording and reproduction systems are reviewed along with the common mathematical models used for representing these devices. Algorithms for processing color images for display and communication are surveyed, and a forecast of research trends is attempted. An extensive bibliography is provided.

Digital color imaging

Perceptual criteria for image quality evaluation

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

This paper surveys current technology and research in the area of digital color imaging. In order to establish the background and lay down terminology, fundamental concepts of color perception and measurement are first presented us-ing vector-space notation and terminology. Present-day color recording and reproduction systems are reviewed along with the common mathematical models used for representing these devices. Algorithms for processing color images for display and communication are surveyed, and a forecast of research trends is attempted. An extensive bibliography is provided.

Digital Color Imaging

A comparative study of different CSFs (contrast sensitivity functions) as to their suitability for the formulation of quality measures in halftoning is presented. The evaluation of the different CSFs is implemented by weighting with each CSF the frequency-domain halftoning error of 44 halftone images, and then comparing the resulting weighted errors with the results of a psychovisual test. Comparison with psychovisual results indicates that the following factors significantly improve the performance of the CSF: incorporation of information about the printing device and the viewing conditions in the quantitative metric; incorporation of information about the angular sensitivity of the visual system: and utilization of a lowpass CSF instead of a bandpass one. >

Evaluation of contrast sensitivity functions for the formulation of quality measures incorporated in halftoning algorithms

The visibility of binary image noise at low-to-medium dot densities of current binary printers, i.e 300-400 dots/in, is not subthreshold. Standard halftoning algorithms such as clustered-dot or dispersed-dot dither produce periodic patterns at these dot densities that are easily visible at normal viewing distances in uniform areas. A novel method of halftoning computer-generated uniform areas that reduces noise visibility by using a database of minimum visual modulation bit patterns is introduced. Applications include all paint-by-numbers prints such as those that offer tint-fill or object highlighting. >

L.A. Ray

Papers

Design of minimum visual modulation halftone patterns