Green-noise digital halftoning

• Published in: Proceedings of the IEEE Vol. 86; no. 12; pp. 2424 - 2444
• Main Authors: Lau, D.L., Arce, G.R., Gallagher, N.C.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.12.1998; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Degradation; Exact sciences and technology; Filters; Image processing; Information, signal and communications theory; Noise generators; Output feedback; Pattern analysis; Pixel; Printing; Signal processing; Statistical analysis; Statistics; Telecommunications and information theory; White noise; Image quality; Frequency modulation; Statistical analysis; Image processing; Power spectral density; Amplitude modulation; Digital image; Spatial resolution; Spectral analysis; Half tone image; Pixel
• ISSN: 0018-9219; 1558-2256
• DOI: 10.1109/5.735449

In this paper, we introduce the concept of green noise-the multifrequency component of white noise-and its advantages over blue noise for digital halftoning. Unlike blue-noise dither patterns, which are composed exclusively of isolated pixels, green-noise dither patterns are composed of pixel-clusters making them less susceptible to image degradation from nonideal printing artifacts such as dot-gain. Although they are not the only techniques which generate clustered halftones, error-diffusion with output-dependent feedback and variations based on filter weight perturbation are shown to be good generators of green noise, thereby allowing for tunable coarseness. Using statistics developed for blue noise, we closely examine the spectral content of resulting dither patterns. We introduce two spatial-domain statistics for analyzing the spatial arrangement of pixels in aperiodic dither patterns, because green noise patterns may be anisotropic, and therefore spectral statistics based on radial averages may be inappropriate for the study of these patterns.