The Error Diffusion Halftoning Using Local Adaptive Sharpening Control

Nae-Joung KWAK  Wun-Mo YANG  Jae-Hyuk HAN  Jae-Hyeong AHAN  

IEICE TRANSACTIONS on Information and Systems   Vol.E87-D   No.12   pp.2888-2892
Publication Date: 2004/12/01
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: LETTER
Category: Image Processing and Video Processing
halftoning,  error diffusion,  sharpening,  edge enhancement,  

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Digital halftoning is used to quantize a grayscale image to a binary image. Error diffusion halftoning generates a high-quality binary image, but also generates some defects such as the warm effect, sharpening, and so forth. To reduce these defects, Kite proposed a modified threshold modulation method that utilizes a multiplicative parameter for controlling sharpening. Nevertheless, some degradation was observed near the edges of objects with a large luminance change. In this paper, we propose a method of controlling the multiplicative parameter in proportion to the magnitude of the local edge slope. The results of computer simulation show a greater reduction of sharpening in the halftone image. In particular, there is a great improvement in the quality of the edges of objects with a large luminance change.