Simplified ink spreading equations for CMYK halftone prints

Bugnon, Thomas; Brichon, Mathieu; Hersch, Roger D.

doi:10.1117/12.761710

Cited by 10 publications

(10 citation statements)

References 13 publications

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“…al. [12], in the case of CMYK prints, 20 ink spreading curves and therefore 20 calibration halftones are sufficient. For 20 instead of 32 calibration halftones, the number of independent 2-by-2 patterns is therefore 116 instead of 176.…”

Section: Predicting the Eynsn Calibration Patch Reflection Spectramentioning

confidence: 99%

Calibrating the ink spreading curves enhanced Yule-Nielsen modified spectral Neugebauer model with the two-by-two dot centering printer model

Rossier

Hersch

2009

SPIE Proceedings

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The Yule-Nielsen modified spectral Neugebauer model enhanced for accounting for ink spreading in the different ink superposition conditions (EYNSN) requires measuring the reflectances of halftone calibration patches in order to compute the ink spreading curves mapping nominal ink surface coverages to effective ink surface coverages. Spectral measurements of dozens of halftone patch reflectance spectra for each considered halftoning method, screen shape or screen frequency variant is cumbersome and time consuming. As an alternative, we compute automatically the reflectance of the calibration patches necessary to establish the ink spreading curves by making use of the two-by-two dot centering model (abbreviated "2-by-2"). The two-bytwo dot centering model requires its own set of calibration patches, among which a very small subset is necessary for predicting the reflectance of the EYNSN calibration patches. For a given combination of printer, paper and inks, using only 68 two-by-two calibration patches for the three CMY inks, respectively 118 twoby-two calibration patches for the four CMYK inks, we are able to predict the reflection spectra of most classical halftone screens and at many different frequencies. We compare the results of predictions where the EYNSN model calibration patches are measured or are predicted with the two-by-two dot centering model. For 125 (CMY) and 625 (CMYK) uniformly distributed patches printed with an ink-jet printer at three different screen frequencies (75lpi, 100lpi and 125lpi), the mean reflectance prediction accuracy is similar, i.e. the decrease in accuracy due to the two-by-two prediction of EYNSN calibration patch reflectance is less than ΔE 94 =0.4.

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Section: Predicting the Eynsn Calibration Patch Reflection Spectramentioning

confidence: 99%

Calibrating the ink spreading curves enhanced Yule-Nielsen modified spectral Neugebauer model with the two-by-two dot centering printer model

Rossier

Hersch

2009

SPIE Proceedings

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“…However, the models can be extended to four inks [15]. With three inks we have 2 3 8 full-tone colorants (also called Neugebauer primaries) corresponding to all superposition combinations of 0% and 100% ink surface coverages.…”

Section: Ink-spreading Enhanced Yule-nielsen Modified Spectral Neugebmentioning

confidence: 99%

Spectral Neugebauer-based color halftone prediction model accounting for paper fluorescence

Hersch¹

2014

Appl. Opt.

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We present a spectral model for predicting the fluorescent emission and the total reflectance of color halftones printed on optically brightened paper. By relying on extended Neugebauer models, the proposed model accounts for the attenuation by the ink halftones of both the incident exciting light in the UV wavelength range and the emerging fluorescent emission in the visible wavelength range. The total reflectance is predicted by adding the predicted fluorescent emission relative to the incident light and the pure reflectance predicted with an ink-spreading enhanced Yule-Nielsen modified Neugebauer reflectance prediction model. The predicted fluorescent emission spectrum as a function of the amounts of cyan, magenta, and yellow inks is very accurate. It can be useful to paper and ink manufacturers who would like to study in detail the contribution of the fluorescent brighteners and the attenuation of the fluorescent emission by ink halftones.

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“…6/32 yielding a total of 32 ink spreading curves. However, since any halftone superposed with solid black yields a reflection spectrum very close to the reflection spectrum of solid black, ink spreading curves where one ink halftone is superposed with solid black are discarded 7 . Table I lists the 20 ink spreading curves considered.…”

Section: Ink Spreading Curvesmentioning

confidence: 99%

Calibrating ink spreading curves by optimal selection of tiles from printed color images

Bugnon¹,

Hersch²

2012

J. Electron. Imaging

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The Yule-Nielsen modified spectral Neugebauer model (YNSN) enables predicting reflectance spectra from ink surface coverages of halftones. In order to provide an improved prediction accuracy, this model is enhanced with an ink spreading model accounting for ink spreading in all superposition conditions (IS-YNSN). As any other spectral reflection prediction model, the IS-YNSN model is conceived to predict the reflection spectra of colorconstant patches. Instead of color-constant patches, we investigate if tiles located within color images can be accurately predicted and how they can be used to facilitate the calibration of the ink spreading model. In the present contribution, we detail an algorithm to automatically select image tiles as uniform as possible from color images by relying on their CMY or CMYK pixel values. The tile selection algorithm incorporates additional constraints relying on surface coverages of the inks. We demonstrate that an ink spreading model calibrated with as few as 5 to 10 optimally chosen image tiles allows the corresponding YNSN model to provide accurate spectral predictions. 1 1 This is an extended version of a paper previously published at the SPIE/IS&T

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Simplified ink spreading equations for CMYK halftone prints

Cited by 10 publications

References 13 publications

Calibrating the ink spreading curves enhanced Yule-Nielsen modified spectral Neugebauer model with the two-by-two dot centering printer model

Calibrating the ink spreading curves enhanced Yule-Nielsen modified spectral Neugebauer model with the two-by-two dot centering printer model

Spectral Neugebauer-based color halftone prediction model accounting for paper fluorescence

Calibrating ink spreading curves by optimal selection of tiles from printed color images

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