The Effect of Multiple Internal Reflections on the Densities of Half-tone Prints on Paper*

Clapper, F. R.; Yule, J. A. C.

doi:10.1364/josa.43.000600

Cited by 112 publications

(81 citation statements)

References 4 publications

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“…The n parameter is an empirical parameter fitted according to the considered printing technology, dithering method, paper, and inks. The second approach is based on the Clapper-Yule equation, derived from an optical model accounting for the reflectance of the paper substrate and the absorbance of the inks [4]. Recent extensions provide very good predictions for a wide range of diffusing supports and printing technologies [5].…”

Section: Introductionmentioning

confidence: 99%

Yule–Nielsen based recto–verso color halftone transmittance prediction model

Hébert

Hersch

2011

Appl. Opt.

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Section: Introductionmentioning

confidence: 99%

Yule–Nielsen based recto–verso color halftone transmittance prediction model

Hébert

Hersch

2011

Appl. Opt.

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“…The original MetallicArt technique is based on an extension of the Clapper-Yule spectral reflection prediction model. 3 This extension incorporates special parameters to take into account specificities of the silver ink such as large ink trapping and a raised metallic reflection spectrum in the presence of other inks. 1 These specificities increase the complexity of the model.…”

Section: Ink Spreading Enhanced Yule-nielsen Modified Spectral Neugebmentioning

confidence: 99%

Enhancing the Specular Effect of Metallic Color Prints by Reducing the Use of Yellow Ink

Bugnon

Maesani²,

Hersch³

2011

jist

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Abstract. The MetallicArt technique is used as a visual security feature to hide patterns in CMY images using an additional silver ink. The patterns are hidden under nonspecular viewing conditions and visible under specular viewing conditions. By varying the amount of silver ink, the authors control the intensity of the specular reflection of the printed pattern. Using a spectral reflection prediction model, they can constrain the maximization of the silver ink (S) in order to keep the color difference between the original CMY color and the fitted CMYS color under a given threshold, ensuring that the pattern is hidden under nonspecular viewing conditions. When the printing device requires the inks to be UV cured, the leafing effect of the silver ink is reduced. This also reduces the specular reflection of the silver ink, which becomes comparable to the specular reflection of the yellow ink. Since both specular reflections are similar, it is difficult to distinguish the embedded patterns under specular viewing conditions when both inks are present. The authors, therefore, propose a new algorithm to embed patterns in CMY images that not only maximizes silver but also minimizes yellow. Experimental results show that the proposed algorithm enhances the visibility of the patterns under specular viewing conditions, allowing the use of MetallicArt when the printing device requires UV curing. INTRODUCTIONWhen light hits a cyan, magenta, and yellow halftone print, it is partly absorbed by the ink layer and partly diffused by the paper substrate, except for the small specular reflection that occurs at the Fresnel interface between air and paper. Although this represents only an approximation of the real phenomena, it has been at the foundation of spectral reflection prediction models and works well in practice.This assumption does not hold for metallic inks. These inks are opaque and reflect most of the light. The incident light does not reach the paper and remains within a relatively narrow cone. The resulting strong specular reflection has been used to hide metallic patterns in normal CMY images, a technique called MetallicArt.1 Using silver ink, this technique consists in determining the image pixels located within a given pattern and to replace their original CMY coverages by CMYS (cyan, magenta, yellow, and silver) coverages containing as much metallic ink as possible, while preserving the original CIELAB color under nonspecular viewing conditions. The

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“…Recently, Rousselle et al 7 proposed a different approach, relying on an extended Clapper-Yule model, 8,9 which modeled variable dot size by variable ink thicknesses. While these research approaches gave interesting insights into the effects of ink thickness variations and the interaction with the paper, they either did not provide sufficient accuracy or were not adapted to our problem, namely, the reflectance prediction of paper dyed with ink mixtures at variable concentrations.…”

Section: Related Workmentioning

confidence: 99%

“…(6), S m according to Eqs. (8) and (10), and the actual mixture reflectance R m according to Eq. (1).…”

Section: Backward and Forward Predictionsmentioning

confidence: 99%

Predicting the Reflectance of Paper Dyed with Ink Mixtures by Describing Light Scattering as a Function of Ink Absorbance

Rousselle¹,

Hébert²,

Hersch³

2010

jist

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The Effect of Multiple Internal Reflections on the Densities of Half-tone Prints on Paper*

Cited by 112 publications

References 4 publications

Yule–Nielsen based recto–verso color halftone transmittance prediction model

Yule–Nielsen based recto–verso color halftone transmittance prediction model

Enhancing the Specular Effect of Metallic Color Prints by Reducing the Use of Yellow Ink

Predicting the Reflectance of Paper Dyed with Ink Mixtures by Describing Light Scattering as a Function of Ink Absorbance

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