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Proceedings Paper

Error diffusion algorithm with output position constraints for homogenous highlight and shadow dot distribution
Author(s): Gabriel G. Marcu
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Paper Abstract

In the conventional error diffusion, non homogeneous arrangement of dots ('worm' artifacts) may occur in the binary image for the highlight and shadow gray regions. In order to eliminate the 'worms' artifacts and preserve the advantages of error diffusion for rendering the middle tones, the proposed method introduces spatial constraints that conduct to more uniform arrangement of dots. In the proposed method, for a current pixel with a gray level in the shadow or highlight region, a dot is placed only if a minimum distance between the current position and the neighbor dots is satisfied. If the distance constraint is not satisfied, the placement of the current dot is postponed and the quantizer error is diffused to the unprocessed pixels. For an input shadow or highlight gray level at the current location, the distance constraint consists of checking if another dot is encountered along a roadmap associated to the current location for a length dependent on the gray level to be represented. The roadmap is defined such that it enlarges from the current location as the gray level to be represented is closer to the extreme limits of the gray level range. The minimum distance from the current dot (black or white) to its neighbors increases as long as the gray level to be represented is closer to the extreme limits of the gray level range (that is, closer to 0% or 100%). The algorithm represents a practical implementation of the output feedback control method proposed by Levien. In term of quality, the proposed method offers equivalent results with the threshold modulation using an imprint function proposed by Eschbach.

Paper Details

Date Published: 2 January 1998
PDF: 12 pages
Proc. SPIE 3300, Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts III, (2 January 1998); doi: 10.1117/12.298297
Show Author Affiliations
Gabriel G. Marcu, Apple Computer, Inc. (United States)


Published in SPIE Proceedings Vol. 3300:
Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts III
Giordano B. Beretta; Reiner Eschbach, Editor(s)

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