Ms. Frederique Crete Profile

Frederique Crete

at STMicroelectronics

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Publications (4)

Proceedings Article | 12 February 2007 Paper

The blur effect: perception and estimation with a new no-reference perceptual blur metric

Frederique Crete, Thierry Dolmiere, Patricia Ladret, Marina Nicolas

Proceedings Volume 6492, 64920I (2007) https://doi.org/10.1117/12.702790

KEYWORDS: Linear filtering, Edge detection, Psychophysics, Gaussian filters, Image quality, Video, Statistical analysis, Sensors, Electronic imaging, Calibration

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SPIE Journal Paper | 1 July 2005

Spectral reflection and dot surface prediction models for color halftone prints

Roger David Hersch, Patrick Emmel, Fabien Collaud, Frederique Crete

JEI, Vol. 14, Issue 03, 033001, (July 2005) https://doi.org/10.1117/12.10.1117/1.1989987

KEYWORDS: Reflection, Halftones, Solids, Superposition, Spectral models, Reflectivity, Printing, Thermal modeling, Interfaces, Light scattering

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Proceedings Article | 17 January 2005 Paper

Improving the Yule-Nielsen modified Neugebauer model by dot surface coverages depending on the ink superposition conditions

Roger David Hersch, Frederique Crete

Proceedings Volume 5667, (2005) https://doi.org/10.1117/12.588907

KEYWORDS: Superposition, Halftones, Solids, Reflection, Printing, Spectral models, Light scattering, Interfaces, Statistical modeling, Systems modeling

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Dot gain is different when dots are printed alone, printed in superposition with one ink or printed in superposition with two inks. In addition, the dot gain may also differ depending on which solid ink the considered halftone layer is superposed. In a previous research project, we developed a model for computing the effective surface coverage of a dot according to its superposition conditions. In the present contribution, we improve the Yule-Nielsen modified Neugebauer model by integrating into it our effective dot surface coverage computation model. Calibration of the reproduction curves mapping nominal to effective surface coverages in every superposition condition is carried out by fitting effective dot surfaces which minimize the sum of square differences between the measured reflection density spectra and reflection density spectra predicted according to the Yule-Nielsen modified Neugebauer model. In order to predict the reflection spectrum of a patch, its known nominal surface coverage values are converted into effective coverage values by weighting the contributions from different reproduction curves according to the weights of the contributing superposition conditions. We analyze the colorimetric prediction improvement brought by our extended dot surface coverage model for clustered-dot offset prints, thermal transfer prints and ink-jet prints. The color differences induced by the differences between measured reflection spectra and reflection spectra predicted according to the new dot surface estimation model are quantified on 729 different cyan, magenta, yellow patches covering the full color gamut. As a reference, these differences are also computed for the classical Yule-Nielsen modified spectral Neugebauer model incorporating a single halftone reproduction curve for each ink. Taking into account dot surface coverages according to different superposition conditions considerably improves the predictions of the Yule-Nielsen modified Neugebauer model. In the case of offset prints, the mean difference between predictions and measurements expressed in CIE-LAB CIE-94 ΔE₉₄ values is reduced at 100 lpi from 1.54 to 0.90 (accuracy improvement factor: 1.7) and at 150 lpi it is reduced from 1.87 to 1.00 (accuracy improvement factor: 1.8). Similar improvements have been observed for a thermal transfer printer at 600 dpi, at lineatures of 50 and 75 lpi. In the case of an ink-jet printer at 600 dpi, the mean ΔE₉₄ value is reduced at 75 lpi from 3.03 to 0.90 (accuracy improvement factor: 3.4) and at 100 lpi from 3.08 to 0.91 (accuracy improvement factor: 3.4).

Proceedings Article | 18 December 2003 Paper

Spectral prediction and dot surface estimation models for halftone prints

Roger Hersch, Fabien Collaud, Frederique Crete, Patrick Emmel

Proceedings Volume 5293, (2003) https://doi.org/10.1117/12.526858

KEYWORDS: Halftones, Solids, Reflection, Spectral models, Superposition, Printing, Interfaces, Light scattering, Reflectivity, Systems modeling

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