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Volume: 47 | Article ID: art00005
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Optimal Output Level Selection for Multilevel Halftoning Based on Visual Experiments Using Spatially Modulated Gratings
  DOI :  10.2352/J.ImagingSci.Technol.2003.47.4.art00005  Published OnlineJuly 2003
Abstract

Experiments have shown that multitoning with output levels equally spaced in CIE L* does not produce uniform texture at different gray levels. In this study, psychophysical experiments are described, investigating the influence of spatial modulation on the perception of lightness difference. A variety of different patterns (square wave, checker-board, and 50% blue noise patterns) were tested at various frequencies and amplitudes (contrast). A significant frequency dependent effect was observed where the lightness difference perception is reduced for high frequency modulated gratings at low L* values. The magnitude of this effect is highly related to the frequency of the modulation. There is no evidence to indicate that either modulation type or modulation amplitude has a significant effect on the lightness difference perception. Based on the experimental results, an effective lightness metric (Le*) is derived as a function of spatial frequency. The Le* metric is intended to provide a space that is linearly related to lightness difference perception for frequency modulated patterns. Results from a further visual experiment have verified that multitoning patterns produced using levels that are equally spaced in Le* produces results with more uniform texture visibility across the entire tone scale.

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  Cite this article 

Muge Wang, Kevin J. Parker, Kevin Spaulding, Qing Yu, Rodney Miller, "Optimal Output Level Selection for Multilevel Halftoning Based on Visual Experiments Using Spatially Modulated Gratingsin Journal of Imaging Science and Technology,  2003,  pp 309 - 326,  https://doi.org/10.2352/J.ImagingSci.Technol.2003.47.4.art00005

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