Recherche

Afficher tous les résultats pour

Accueil

Personne

Roger Hersch

À propos
Confidentialité
Mentions légales

Graph Chatbot

Publications associées (70)

Printing color images visible under uv light on security documents and valuable articles

Roger Hersch, Sylvain Chosson, Philipp Donzé

In the present invention, we propose a method of creating fluorescent color images visible under UV light. It relies on the new colorants that can be achieved by superposing ink dots, possibly at a reduced size, in order to avoid quenching effects. It also ...

2008

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

Spectral prediction model for variable dot-size printers

Roger Hersch, Thomas Bugnon

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 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

Calibrating the Yule-Nielsen modified spectral Neugebauer model with ink spreading curves derived from digitized RGB calibration patch images

Roger Hersch, Adish Kumar Singla, Nikhil Garg

The Yule-Nielsen modified spectral Neugebauer model (YNSN) enhanced for accounting for ink spreading in the different ink superposition conditions requires a photospectrometer to measure the reflectances of halftone calibration patches in order to compute ...

2008

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

Simplified Ink Spreading Equations for CMYK Halftone Prints

Roger Hersch, Thomas Bugnon, Mathieu Brichon

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 piles of nonscattering sheets

Roger Hersch, Mathieu Hébert

The present paper investigates the reflection and transmission properties of piles of nonscattering sheets. Using a spectral prediction model, we perform a detailed analysis of the spectral and color variations induced by variations of the number of superp ...

2008

Ray scattering model for spherical transparent particles

Roger Hersch, Mathieu Hébert

2008

Synthesis of superposition images for watches, valuable articles and publicity

Roger Hersch, Sylvain Chosson

The present invention aims at synthesizing superposition images formed either by band moire shapes or by shape level lines for making the information forwarded by valuable articles or by time pieces such as watches and clocks more dynamic, as well as for i ...

2007

A simulator for adaptive parallel applications

Sebastian Gerlach, Roger Hersch, Basile Schäli

Dynamically allocating computing nodes to parallel applications is a promising technique for improving the utilization of cluster resources. Detailed simulations can help identify allocation strategies and problem decomposition parameters that increase the ...

2007

Compositional reflectance and transmittance model for multilayer specimens

Roger Hersch, Mathieu Hébert

We propose a compositional model for predicting the reflectance and the transmittance of multilayer specimens composed of layers having possibly distinct refractive indices. The model relies on the laws of geometrical optics and on a description of the mul ...

2007

Color images visible under UV light

Roger Hersch, Sylvain Chosson, Philipp Donzé

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

Ink thickness variations for the control of color printers

Roger Hersch, Peter Amrhyn

The present invention proposes a method and a computing system for deducing ink thickness variations from spectral reflectance measurements performed on a printing press or on a printer. The computed ink thickness variations enable controlling the ink depo ...

2007

Deducing Ink-Transmittance Spectra from Reflectance and Transmittance Measurements of Prints

Roger Hersch, Mathieu Hébert

The color of prints is mainly determined by the light absorption of the inks deposited on top of paper. In order to predict the reflectance spectrum of prints, we use a spectral prediction model in which each ink is characterized by its spectral transmitta ...

2007

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

Roger Hersch, Thomas Bugnon, Mathieu Brichon

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

An Ink Spreading Model for Dot-On-Dot Spectral Prediction

Roger Hersch, Adish Kumar Singla

Due to increasing printing accuracies and the possibility of printing several droplets at the same pixel location, there is a renewed interest in dot-on-dot printing models. In the present contribution, we improve a dot-on-dot spectral prediction model rel ...

2006

Extension of the Williams-Clapper model to stacked nondiffusing colored coatings with different refractive indices

Roger Hersch, Mathieu Hébert

We propose a model for predicting the reflectance and transmittance of multiple stacked nonscattering coloring layers that have different refractive indices. The model relies on the modeling of the reflectance and transmittance of a bounded coloring layer, ...

Opt. Soc. America2006

Distance preserving flattening of surface sections

Roger Hersch, Laurent Saroul

Curved cross-sections extracted from medical volume images are useful for analyzing nonplanar anatomic structures such as the aorta arch or the pelvis. For visualization and for performing distance measurements, extracted surface sections need to be adequa ...

2006

Reflectance and transmittance model for recto-verso halftone prints

Roger Hersch, Mathieu Hébert

We propose a spectral prediction model for predicting the reflectance and transmittance of recto-verso halftone prints. A recto-verso halftone print is modeled as a diffusing substrate surrounded by two inked interfaces in contact with air (or with another ...

2006

Page 3 sur 4