Summary
International Workshop on Smart Info-Media Systems in Asia
2021
Session Number:RS3
Session:
Number:RS3-5
Simple 3-Level Error Diffusion Method by Using Piecewise Linear Conversion
Shuma Takeda, Yoshiaki Ueda, Takanori Koga, Noriaki Suetake,
pp.144-149
Publication Date:2021/9/20
Online ISSN:2188-5079
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Summary:
Multitoning is to express a continuous tone image with a limited number of the tone. The error diffusion is one of the multitoning methods. A halftone image obtained by 2-level error diffusion has favorable dot distribution and excellent gradation reproducibility. However, in the case of 3-level error diffusion, clipped mid-tones appear. In our previous method, this problem has solved by employing the nonlinear image conversion before the multitoning process. Although this process creates another problem; some dots with inappropriate brightness for the surrounding area occur. As a result, the quantized error between the original image and the resultant image increases. In this paper, we newly propose the 3-level halftoning method that can prevent clipped mid-tones and the dots with inappropriate brightness. In the proposed method, the image conversion function is designed logically, and the problems mentioned above are solved successfully. In the experiments, the proposed method is applied to some natural images and 60 sinewave images. From the subjective and objective evaluations, the effectiveness of the proposed method is shown.