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Roger Hersch

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Publications associées (69)

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Color reproduction, pattern hiding and image alternations with halftone prints on metal

Roger Hersch, Petar Pjanic

We propose new methods for creating color or achromatic images that are printed with classical cyan, magenta, yellow and a white diffusing ink on a metallic substrate. We optimize the surface coverages of the cyan, magenta, yellow and white inks in order t ...

2016

1D moiré shapes by superposed layers of micro-lenses

Jürgen Brugger, Roger Hersch, Valentin Flauraud, Thomas Walger, Théophane Besson

Two superposed layers of transparent cylindrical lenslet gratings create classical moiré fringes, when illuminated from behind. We rely on this observation to conceive special devices made of superposed lenslet gratings that produce animated moirés when th ...

2019

Constrained Acquisition of Ink Spreading Curves From Printed Color Images

Roger Hersch, Thomas Bugnon

Today's spectral reflection prediction models are able to predict the reflection spectra of printed color images with an accuracy as high as the reproduction variability allows. However, to calibrate such models, special uniform calibration patches need to ...

2011

Color images visible under UV light

Roger Hersch, Sylvain Chosson

The present contribution aims at creating color images printed with fluorescent inks that are only visible under UV light. The considered fluorescent inks absorb light in the UV wavelength range and reemit part of it in the visible wavelength range. In con ...

2007

Recovering Neugebauer colorant reflectances and Ink-spreading curves from printed color images

Roger Hersch, Thomas Bugnon

Spectral reflection prediction models, although effective, are impractical for certain industrial applications such as self-calibrating devices and online monitoring because their calibration requires specific color-constant calibration patches. Using the ...

Wiley-Blackwell2014

Color changing effects with cross-halftone prints on metal

Roger Hersch, Petar Pjanic

We propose new methods for creating color varying prints with classical cyan, magenta, yellow inks on a metallic substrate. We use a special crossline halftone with optimized surface coverages of the inks to create color prints on a metallic surface whose ...

2017

Model-Based deduction of CMYK Surface Coverages from Visible and Infrared Spectral Measurements of Halftone Prints

Roger Hersch, Thomas Bugnon

The Yule-Nielsen modified Spectral Neugebauer reflection prediction model enhanced with an ink spreading model provides high accuracy when predicting reflectance spectra from ink surface coverages. In the present contribution, we try to inverse the model, ...

2007

Simplified Ink Spreading Equations for CMYK Halftone Prints

Roger Hersch, Thomas Bugnon

The Yule-Nielsen modified spectral Neugebauer model enables predicting reflectance spectra from surface coverages. In order to provide high prediction accuracy, this model is enhanced with an ink spreading model accounting for physical dot gain. Traditiona ...

2008

Spectral prediction model for color prints on paper with fluorescent additives

Roger Hersch

I propose a model for predicting the total reflectance of color halftones printed on paper incorporating fluorescent brighteners. The total reflectance is modeled as the additive superposition of the relative fluorescent emission and the pure reflectance o ...

2008

Reflectance and transmittance model for recto-verso halftone prints: spectral predictions with multi-ink halftones

Roger Hersch, Mathieu Hébert

We extend a previously proposed spectral reflectance and transmittance prediction model for recto-verso prints to the case of multi-ink halftones. The model takes into account the multiple reflections and the lateral propagation of light within the paper s ...

2009

A New Anti-Counterfeiting Feature Relying on Invisible Luminescent Full Color Images Printed with Lanthanide-Based Inks

Jacques-Edouard Moser, Roger Hersch, Anne-Sophie Chauvin, Julien Alexandre Andres

Europium and terbium trisdipicolinate complexes are inkjet printed onto paper with commercially available desktop inkjet printers. Together with a commercial blue luminescent ink, the red-emitting luminescent ink containing europium and the green-emitting ...

Wiley-Blackwell2014

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

Roger Hersch, Andrea Maesani, Thomas Bugnon

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 ...

2011

Kubelka-Munk model for imperfectly diffuse light distribution in paper

Roger Hersch, Lin Yang

Perfectly diffuse light is a fundamental assumption in the Kubelka-Munk (KM) modeL This assumption is, however seldom fulfilled by real media. In this work, we build a bridge between a weakly absorbing medium with an imperfectly diffuse light distribution ...

2008

Multilayer four-flux matrix model accounting for directional-diffuse light transfers

Roger Hersch, Mathieu Hébert

The four-flux model is a method to solve light radiative-transfer problems in planar, possibly multilayer structures. The light fluxes are modeled as two collimated and two diffuse beams propagating forward and backward perpendicularly to the layer stack. ...

Optical Soc Amer2016

Color changing effects with cross-halftone prints

Roger Hersch, Petar Pjanic

We propose new methods for creating color varying prints with classical cyan, magenta, yellow inks on a metallic specularly reflecting or on a white diffusely reflecting substrate. We use a special cross-line halftone with optimized surface coverages of th ...

2017

Ray scattering model for spherical transparent particles

Roger Hersch, Mathieu Hébert

By printing a variable number of droplets onto the same pixel location, ink jet printers produce pixels at variable dot-sizes yielding several darkness levels. Varying the number of printed droplets affects the ink volume deposited onto the substrate. In t ...

2008

Spectral prediction model for variable dot-size printers

Roger Hersch, Thomas Bugnon

2008

Synthesis of authenticable luminescent color halftone images

Roger Hersch, Romain Rossier

The present invention enables creating authenticable multi-ink luminescent continuous tone color halftone images offering means of verifying their authenticity. The invented luminescent color halftone image synthesizing techniques enable increasing the att ...

2012

Dynamic Testing of Flow Graph Based Parallel Applications

Roger Hersch, Basile Schäli

In message-passing parallel applications, messages are not delivered in a strict order. The number of messages, their content and their destination may depend on the ordering of their delivery. Nevertheless, for most applications, the computation results s ...

ACM2008

Revealing Information by Averaging

Sabine Süsstrunk, Roger Hersch, Mahmut Sami Arpa

We present a method for hiding images in synthetic videos and reveal them by temporal averaging. The main challenge is to develop a visual masking method that hides the input image both spatially and temporally. Our masking approach consists of temporal an ...

Optical Soc Amer2017