Françoise Viénot

Muséum National d'Histoire Naturelle · Centre de recherche sur la conservation des collections (CRCC)

The analysis of the current safety standards for electric toys showed that the normative intensity limits for visible light emitted by LEDs integrated in toys are overestimated. These limits were originally set in a scientific article published in 2012 that was adapted into the international safety standard published in 2017, and into the subsequen...

The analysis of the current safety standards for electric toys showed that the normative intensity limits for visible light emitted by LEDs integrated in toys are overestimated. These limits were originally set in a scientific article published in 2012 that was adapted into the international safety standard published in 2017, and into the subsequen...

The present review draws together wide-ranging studies performed over the last decades that catalogue the effects of artificial-light-at-night (ALAN) upon living species and their environment. We provide an overview of the tremendous variety of light-detection strategies which have evolved in living organisms - unicellular, plants and animals, cove...

An appraisal of the effects on human health and the environment of LEDs by the authors of the report of the French health agency ANSES published in 2019.

Recherche et analyse bibliographique, Évaluation du niveau de preuve des effets sanitaires, Caractérisation de l’exposition, Évaluation des risques pour la santé humaine

Photic stimulation of rods, cones and intrinsically photosensitive melanopsin-containing retinal ganglion cells (ipRGCs) mediates non-visual light responses, including entrainment of circadian rhythms and pupillary light reflex. Unlike visual responses to photic stimulation, the cerebral correlates of non-visual light responses in humans remains el...

Cone fundamentals is the name given to the relative spectral sensitivity of long-wave sensitive, medium-wave sensitive and short-wave sensitive cones. Cone fundamentals represent the spectral absorptances of the retinal photopigments in the cones multiplied by the spectral transmittances of the ocular media through which light passes to reach the r...

The generic framework of metamerism implies that the number of sensors is smaller than the dimension of the stimulus. The metameric black paradigm was introduced by Wyszecki [Farbe 2, 39 (1953)] and developed by Cohen and Kappauf [Am. J. Psychol. 95, 537 (1982)]. Within a multireceptor and multiprimary scheme, we investigate how far the choice of i...

Keywords: Sorghum Wheat Leaf Surface roughness BRDF BRF Reflectance Conoscope Azimuthal anisotropy Optical properties Goniometer Physical model Refractive index Leaf reflectance of monocotyledons generally displays a strong azimuthal anisotropy due to the longitudinal orientation of the veins. The Cook and Torrance (CT) bidirectional reflectance di...

Among the identified risk factors of age-related macular degeneration, sunlight is known to induce cumulative damage to the retina. A photosensitive derivative of the visual pigment, N-retinylidene-N-retinylethanolamine (A2E), may be involved in this phototoxicity. The high energy visible light between 380 nm and 500 nm (blue light) is incriminated...

Introduction Physiological Basis The XYZ Colorimetry: The Benchmark Model of CIE LMS Colorimetry Colors in Their Context Conclusion Bibliography

A multispectral imaging system enabling biological tissue identifying and differentiation is presented. The measurement of β(λ) spectral radiance factor cube for four tissue types (beef muscle, pork muscle, turkey muscle and beef liver) present in the same scene was carried out. Three methods for tissue identification are proposed and their relevan...

This study focuses on the directionality of wheat leaf reflectance as a function of leaf surface characteristics. Wheat leaf BRF measurements were completed under 45° zenith illumination angle in three visible broad spectral bands with a conoscope that provides very high angular resolution data over a large portion of the whole hemisphere, includin...

Any stimulus can be described as composed of two components—a fundamental color stimulus that controls the three cone responses and a metameric black that has no effect on cones but can drive photoreceptors other than cones [e.g., rods and melanopsin expressing retinal ganglion cells (ipRGCs)]. The Cohen and Kappauf [Am. J. Psychol. 95, 537 (1982)1...

In order to build biological tissues spectral characteristics database to be used in a multispectral imaging system a tissues optical characterization bench is developed and validated. Several biological tissue types have been characterized in vitro and ex vivo with our device such as beef, turkey and pork muscle and beef liver. Multispectral image...

A procedure to enhance the faded colours of museums artefacts is presented. The method is based on adjusting the spectral profile of the light while maintaining a given white colour of the illumination. The procedure is tested using colour LED clusters and a series of damaged samples and their good condition counterparts. The intensity of the three...

In the context of color perception on modern wide-gamut displays with narrowband spectral primaries, we performed a theoretical analysis on various aspects of physiological observers proposed by CIE TC 1-36 (CIEPO06). We allowed certain physiological factors to vary, which was not considered in the CIEPO06 framework. For example, we analyzed that t...

Increased interest in color management has resulted in more options for the user to choose between for their color management needs. We propose an evaluation process that uses metrics to assess the quality of ICC profiles, specifically for the perceptual rendering intent. The primary objective of the perceptual rendering intent, unlike the media-re...

Premier rapport d'expertise collective menée par l'ANSES sur les impacts sanitaires des LED.

In addition to rods and cones, the human retina contains melanopsin which has been identified recently in the body and dendrites of a few ganglion cells. The intrinsically photosensitive retinal ganglion cells (ipRGCs) are good candidates for controlling the tonic pupil aperture but their spectral sensitivity is close to those of rods and S-cones w...

Observers were invited to report their degree of satisfaction on a 6-point semantic scale with respect to the conformity of a test colour with a white reference colour, simultaneously presented on a PDP display. Eight test patches were chosen along each of the +a*, -a*, +b*, -b* axes of the CIELAB chromaticity plane, at Y = 80 ± 2 cd.m(-2) . Experi...

In everyday life, the visual system is remarkably good at recognizing materials across a wide range of viewing conditions. This paper addresses the problem of identifying real samples of materials from appearance. Here, we consider gloss as an appearance attribute that could reveal certain information about object properties. We prepared twelve sam...

In order to determine the chromatic contrast sensitivity function, the luminance equilibrium of chromatic pairs should be evaluated with the actual visualization display. This evaluation should be done at different eccentricities when the visual stimulations are DOGs (Difference Of Gaussians), because the spatial frequency variation modifies the sp...

Introduction: white light and visual qualityNotions of colorimetry and photometryObtaining white light with LEDsColor rendering of sourcesWorks on quality of light from LEDsApplications of LEDs to lightingConclusion: advantages, precautions and perspectivesAcknowledgementsBibliography

A uni® ed system of photometry is proposed that is based on human vision and allows the speci® cation of visual stimuli at all light levels. To be useful, however, photometry can never be entirely synonymous with vision. Additivity is an essential characteristic of photometry, yet many visual responses, such as brightness matching, incorporate visu...

This chapter describes an experiment aimed at examining the respective contribution of achromatic contrast and isoluminant chromatic contrasts for generating subjective colours. It compares the efficiency of cone contrasts that are manipulated in an additive mode or in an antagonistic mode to differentiate subjective colours produced by different s...

Light-emitting diode (LED) technology offers the possibility of obtaining white light, despite narrow-band spectra. In order to characterize the colour discrimination efficiency of various LED clusters, we designed a classification test, composed of 32 caps equally distributed along the hue circle at about 3 ΔE* ab-unit intervals. Forty normal colo...

Comme l'enfant mouille un galet pour le rendre attractif, ce qui ne durera qu'un moment, le lapidaire a su tailler et polir la pierre pour obtenir un éclat durable. Cet éclat auquel l'oeil est sensible, quel est-il ? – Un point lumineux, une couleur vive, un motif contrasté. Ce chapitre a pour objet de présenter des méthodes physiques de caractéris...

The advantages of LED lighting are discussed. We report experiments where observers graded the quality of several light-emitting diode (LED) illuminations. One experiment is based on color discrimination and two experiments are based on the judgement of appearance. We conclude that clusters with red, green, blue, and/or amber LEDs impair color disc...

Color matches related to various retinal areas are explored systematically. When viewing a 30° bipartite field, the observer match is a balance between a peripheral and a central match, slightly in favor of the peripheral assessment. The macular pigment is responsible for most of the changes observed between the foveal matches and the peripheral on...

This paper describes equipment designed to measure the color-matching functions of a human observer, together with the results obtained. Its future potentialities are discussed, as well as its limitations, accúracy, and reliability. The results obtained are in close agreement with the CIE 1964 Standard Colorimetric Observer data and will enable a s...

The link between colorimetry and physiology Discussion and perspectives Conclusion Acknowledgments References

The paper is copyright by CIE. It is available from national committees.

Shift in the wavelength of peak sensitivity of the cone photo pigments is a major cause of inter-individual variations in the Rayleigh match. Normal color observers performed multiple Rayleigh matches (i.e., a series of seven Rayleigh-type color matches using various sets of test and primary lights) in order to derive estimates of the M- and L-phot...

Vision screening of school children at 5-6 years of age must include color vision screening. X-linked dyschromatopsia is the most frequent disorder affecting 8% of boys and 0.4% of girls. This paper presents the physiology of these deficiencies caused by an alteration of the spectral absorption properties of one of the cone pigments (protanomalous...

Le dépistage de la qualité de la vision des enfants en âge d′être scolarisés (à partir de 5-6 ans) doit comprendre un examen de la vision des couleurs, les déficiences liées au chromosome X étant les plus fréquentes (8 % des garçonnets et 0,4 % des fillettes). Cet article présente les bases neurophysiologiques de ces déficiences, en relation avec l...

In order to perform quantitative evaluation of a camera colour measurement quality, two characterization approaches were performed and compared: measuring the spectral sensitivity of the R G B channels, and using a least square fitting of L*a*b* coordinates of a collection of reference samples.

We studied the preference judgment of pictorial images by image experts and naive observers. We first asked image experts to improve pictorial images the way they preferred. Then, we showed the different versions of each image to naive observers and asked them which version they preferred. To enhance an image, an expert divides it into large areas...

We deal with the regulation of chromatic contrast when the induction of a second stimulus (one of five neighboring surrounds) opposes the induction from a first stimulus (one of two remote vivid peripheral fields). Using a hue cancellation judgment, we show that, although every neighboring surround that we used has the same average chromatic conten...

We measured the discrimination efficiency of three LED clusters (RGB, RGB + Amber, cool White + Amber) using the desaturated Lanthony-Panel D15 colour vision test. Compared with a continuous spectrum illumination, all LED clusters impair colour discrimination, with a severe impairment for RGB LED cluster. 1. PURPOSE LED technology offers light sour...

The contribution of binocular vision to gloss perception has been suggested in the literature [1][2]. A simple assumption is that binocular disparity plays a role in gloss perception. Nevertheless, everyone can verify that his ability to judge the gloss of a surface is maintained by closing an eye. We have conducted a psychophysical experiment to q...

Chromatic contrast occurs when a color patch is surrounded by a chromatic field [1,2]. Several studies demonstrate the importance of variation within the surrounding field, in addition to the effect of chromaticity of the field on color appearance [3,4,5,6]. The chromatic appearance of a target is tested under an equilibrium condition resulting fro...

Gloss is an attribute of visual appearance that originates from the geometrical distribution of the light reflected by the surface. We used the maximum likelihood difference scaling (MLDS) procedure (L.T. Maloney & J. N. Yang, 2003) to estimate gloss scales over an extended range. Observers' judgments were obtained for a series of 10 black, coated...

Computer graphics provides a powerful tool to study lighting and visual signalling as well as information requirements of transport and traffic. However, real-world luminance dynamic range is often too high for display devices. Compression must be achieved using a so-called "tone-mapping" operator, and the question arises whether tampering with the...

We have studied the preference judgement of pictorial images with two types of population: image experts and naive observers. We used eight images of indoor and outdoor scenes. The images were first presented to image experts working in pre-press companies. We asked them to improve the images the way they preferred and to comment on their manipulat...

The scope of TC 1-36 is to supplement the CIE colorimetric observers with color matching data that make a clear connection between the color specification and the underlying physiology. After careful examination of color matching data, TC 1- 36 has agreed on proposing a continuous fundamental observer with data from 10 degree(s) to 1 degree(s). The...

This study aims at establishing the relationship between the spectral transmission characteristics of tinted ophthalmic lenses and the visual percept of the observer looking through. We hypothesize that the rating of tinted lenses originates from what the observer sees rather than what the glass looks like. We develop a model for color acceptance b...

Michel-Eugène Chevreul (1786–1889) did major scientific work in the fields of chemistry and colour and pioneered the study of simultaneous contrast. His book De la loi du contraste simultané des couleurs (The Principles of Harmony and Contrast of Colours) was published in 1839. Here, his studies pertained to simultaneous contrast, when two or more...

Gloss is a visual attribute, which, as well as color, provides qualitative information on the surrounding objets. The relevant physical quantity for gloss measurement is the BRDF that characterizes the geometrical distribution of the reflected light on the sample. We hypothesize that the light reflection on a glossy sample is split in 2 parts. The...

Primates are apparently unique amongst the mammals in possessing trichromatic colour vision. However, not all primates are trichromatic. Amongst the haplorhine (higher) primates, the catarrhines possess uniformly trichromatic colour vision, whereas most of the platyrrhine species exhibit polymorphic colour vision, with a variety of dichromatic and...

We have proposed colormaps to replace a widely used 216 colors palette in order to allow a designer with normal color vision to simulate the colors seen by dichromats. As dichromats lack one class of cone photo pigment, they confuse colors that differ only in the excitation of the missing class of photo pigment. The method is based on the LMS color...

Subjective colours produced by the achromatic pattern of a rotating Benham's disc depend upon the phase relationship and the contrast between the luminous signals of the arc and the background. By studying the effect of luminance and spectral adaptation with different illuminations specified in terms of LMS cone excitation, we determine whether par...

Michel–Eugène Chevreul (1786–1889) made major scientific contributions to the fields of chemistry and colour. Among other works, he invented a three-dimensional colour classification system, which he used to manufacture a colour atlas showing colour circles and monochrome lightness scales. We have investigated Chevreul's classification system in or...

Two major factors causing a change in colour matches between large and small fields are macular pigmentation and cone outer-segment lengthening. We have simulated the effect of the macular pigment optical density (o.d.) and of the cone effective o.d. on colour matches and demonstrated that ignoring the change of cone o.d. between the fovea and the...

The authors investigated the shape of the contrast sensitivity function of the human visual system for red, green and blue stimuli under selective chromatic adaptation, and, at eccentricities of 0 degrees , 13 degrees and 26 degrees . The results are compared to those obtained for an achromatic test, at the same eccentricities. The stimuli (diamete...

We propose replacement colourmaps that allow a designer to check the colours seen by protanopes and deuteranopes. Construction of the colourmaps is based on the LMS specification of the primaries of a standard video monitor and has been carried out for 256 colours, including 216 colours that are common to many graphics applications of MS Windows an...

It is a long-standing hypothesis that primate trichromacy evolved to help fruit-eating primates find fruits amongst leaves. We measured the reflectance spectra of fruits eaten by a trichromatic primate, Alouatta seniculus, in the rainforest of French Guiana, as well as those of the leaves that form the natural background to fruits. We develop a met...

A metameric match may be accepted by one observer but rejected by another, indicating that the colour vision of the two observers is different. We analysed the variations of normal colour vision using metameric surfaces. First, we modelled the matches of a theoretical colour-normal observer on the Davidson and Hemmendinger (D&H) colour rule (Kaiser...