Visual performance

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Visual performance using reaction times

Visual performance using reaction times

Visual performance using reaction times Rea, M. S.; Ouellette, M. J. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Toward a model of visual performance: foundations and data

Toward a model of visual performance: foundations and data

Toward a model of visual performance: foundations and data Rea, M. S. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Application of a Relative Visual Performance Model in a Virtual Reality Immersive System

Application of a Relative Visual Performance Model in a Virtual Reality Immersive System

Though, as it appears that there exists a contrast value beyond which performance diminishes, the single threshold contrast value seems to not be enough. Following this idea, the International Commission for Eclairage (ICE), mostly based on the work of H. R. Blackwell [7], designed a model of visual performance. The approach specifies a level of performance in completing a task based on its lighting parameters such as luminance and contrast. It thus serves to establish task lighting standards. The model first computes a level of visibility at which the task is performed and then rates the overall performance. The entry parameters of the model are the difficulty of the task, the age of the observer and the lighting parameters. Its range is quite consequent as it takes in a luminance from 1 to 10000 cd=m 2 . However, it only works for eccentricities lesser than 3 degrees. One main drawback of the model is that it should not be used in interior lighting as light is then mostly directional and specular.
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The Effects of fluorescent lighting filters on skin appearance and visual performance

The Effects of fluorescent lighting filters on skin appearance and visual performance

Other respected lighting investigators, using other methodologies, have reached other conclusions (Ref. 19, 20, 21, 22). (These papers would have received complete peer review: two are journal papers, one is a complete PhD thesis successfully defended, and one is a CIE paper, which would have been reviewed in full prior to acceptance.) These investigations differed from the Berman and Navvab work. In all cases, the task was lit using general room lighting, so that surround and task had the same color temperature and the task was not itself luminous. In Ref. 19, 21, and 22, the range of light sources was smaller than in either Berman's or Navvab's work (across the range of 2700 - 5000 K), although Halonen's thesis included sources of 2900, 3300, 5500, and 9500 K. These investigators did not find effects of spectral composition on visual performance. Our experiment differed yet again in allowing only a near field of view, although both the task and its surround were lit in the same way to the same level.
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The effects of luminous surroundings on visual performance, pupil size, and human preference

The effects of luminous surroundings on visual performance, pupil size, and human preference

Although task surround conditions in this experi- ment did not significantly affect visual performance or perceived readability, measured pupil sizes were significant[r]

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Toward a model of visual performance: a review of methodologies

Toward a model of visual performance: a review of methodologies

Toward a model of visual performance: a review of methodologies Rea, M. S. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Modulation of fluorescent light : flicker rate and light source effects on visual performance and visual comfort

Modulation of fluorescent light : flicker rate and light source effects on visual performance and visual comfort

Dr. Berman and Mr. Benson make a logical error when they state that a priori differences in acuity between the lamp type groups confound the contrast, in that they base their statement about acuity on the dependent measure of visual performance, which could have been influenced by the lamp type. To compare the baseline acuities of participants would require a pretest (initial) measure of acuity based on identical test conditions. We are confident that the groups were comparable in this sense because all participants passed the Titmus vision test with at least 20/20 vision and were subsequently assigned randomly to one of the three groups. This is the standard procedure for a true between-groups experimental design (14,15) . We quote Cook and Campbell, authors of one of the most widely-cited books on research design in the behavioural sciences: "...a properly implemented random assignment procedure will usually result in initially comparable experimental groups..." (Ref. 14, p. 342). It allows us to infer that differences in the outcome measures between the groups were caused by the treatment (lamp type) rather than by pre-existing differences between the groups.
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Separation of the retinal and central contribution to changes in visual performance after light exposure

Separation of the retinal and central contribution to changes in visual performance after light exposure

The critical flicker fusion (CFF) test (58, 81) is one of the methods widely used to assess overall CNS activity. The CFF test determines the temporal threshold below which a high frequency light stimulus is perceived as steady. The mean CFF threshold frequency has been shown to fluctuate according to circadian time with lower values at night (82), but it is not known how or if the b-wave ERG changes affect visual performance and thus CFF thresholds. This could bias the evaluation of CNS activity and may be the explanation for why CFF has often failed to detect existing vigilance impairment (58). Moreover, to our knowledge, the effect of light exposure upon CFF value at night has not been systematically evaluated.
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The CIE visual performance system

The CIE visual performance system

The CIE visual performance system Levy, A. W. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Visual performance with realistic methods of changing contrast

Visual performance with realistic methods of changing contrast

Visual performance with realistic methods of changing contrast Rea, M. S. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Relative visual performance : a basis for application

Relative visual performance : a basis for application

Relative visual performance : a basis for application Rea, M. S.; Ouellette, M. J. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Visual performance, visibility and apparent contrast

Visual performance, visibility and apparent contrast

Visual performance, visibility and apparent contrast Levy, A. W. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Effects of Haidinger's brushes on visual performance

Effects of Haidinger's brushes on visual performance

Effects of Haidinger's brushes on visual performance Rea, M. S. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Procedure to determine background luminance for use in ESI and visual performance methods

Procedure to determine background luminance for use in ESI and visual performance methods

In both methods the background luminance is determined by reference to threshold contrast of the four-minute disc (the visihility reference task) under reference lighting cond[r]

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Modulation of fluorescent light: Flicker rate and light source effects on visual performance and visual comfort

Modulation of fluorescent light: Flicker rate and light source effects on visual performance and visual comfort

Modulation of fluorescent light: Flicker rate and light source effects on visual perfonnance and visual comfort The study by Veitch and McColl(6) ('the authors') primarily investigated t[r]

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On The Performance of Human Visual System Based Image Quality Assessment Metric Using Wavelet Domain

On The Performance of Human Visual System Based Image Quality Assessment Metric Using Wavelet Domain

Keywords: Quality Assessment, Human Visual System, DWT, DFT, Contrast Masking, Entropy Masking 1. INTRODUCTION The aim of an objective image quality assessment is to create an automatic algorithm that evaluates the picture or video quality as a human observer would do. Image quality assessment has been extensively studied during this past few decades and many different objective criteria have been built. The quality metrics based on models of the Human Visual System (HVS) are an important part of the different approaches in image quality assessment. HVS models may be classified into mono-channel or multi-channel models. This work focus on the latter. In order to simulate the multi-channel behavior of the HVS and to well qualify the visual masking effects, this kind of quality metrics rests on a perceptual subband decomposition. This decomposition is often realized in the frequency domain like Fourier domain. The use of Fourier domain leads to good performances, but with high computational complexity. One solution to deal with this would be to use a spatial transform like a wavelet transform. Nevertheless, the correspondence between the visual system and the wavelet domain is known to be only approximate 1 . 2 This issue results in non-optimal visual performance, especially in the setting up of the visual masking. But even if the visual masking effects are non-optimal, what is the decrease in performance in terms of quality assessment?
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[PDF] Cours de Visual Basic.Net pour débutants ou anciens - Cours visual basic

[PDF] Cours de Visual Basic.Net pour débutants ou anciens - Cours visual basic

Microsoft Visual Basic . Net - Août 2003 45/139 attendues pour les objets seront implémentées sous la forme de méthode : c’est à dire une fonction ou une procédure liée à un type d’objet (les classes) et dépendante. Par exemple, la fonction calculer age perd tout son sens si vous ne l’appelez pas à partir d’une personne existante (objet). De ce fait, nous obtenons un programme structuré logiquement et grandement clarifié.

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Robust image-based visual servoing using invariant visual information

Robust image-based visual servoing using invariant visual information

3.1.2. Rotation vector feature from two points in the image Recently, in [7] and [19], an angle-axis representation of a rotation matrix R computed from two projected points on the sphere has been considered to control rotational motions for visual servoing application. The idea behind the rotation formula given in these works is equivalent to attaching an or- thonormal frame basis to each camera pose using two projected points onto the unit sphere. More precisely, let P s 1 and P s 2 be two projected points on

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Photometric visual servoing

Photometric visual servoing

In this paper, we summarize several previous works. In [12], the analytic computation of the interaction matrix related to the luminance for a Lambertian scene is provided, only positioning tasks have been considered. In [13], this matrix has been computed considering a lighting source mounted on the camera and the use of the Blinn-Phong illumination model (a simplified model of the Phong model detailed in the next section), only tracking tasks have been considered. In [14], the Phong model has been used, only positioning tasks have been considered. In addition, these works refer to [15] where details concerning analytic computations are given. Note that in [16], although this is also a direct visual servoing approach, the considered features used in the control law are very different. In this paper, we specifically focus on the way the visual servoing problem has been turned into an optimization problem. More precisely, we analytically analyse the cost function to minimize in order to derive an efficient control law. Moreover, additional experimental results than those described in our previous works are presented, as for example a comparison between classical 2D geometric visual features and the use of the luminance. We will show that by using luminance much lower positioning errors can be obtained.
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[PDF] Support de cours sur le Visual basic et l’acces aux donnees | Cours visual basic

[PDF] Support de cours sur le Visual basic et l’acces aux donnees | Cours visual basic

Vous pouvez librement distribuer toutes applications ou tous composants redistribuables créés avec Microsoft® Office Developer . Notez que comme Microsoft® FrontPage® et Microsoft® Outlook® gèrent uniquement des projets fondés s ur des profils utilisateur, l'Assistant Empaquetage ne peut pas créer d'empaquetage en utilisant ces produits. Vous pouvez cependant créer un empaquetage et déployer des projets autonomes comme les projets compléments, créés dans l'environnement Microsoft® Visual Basic® pour Applications (VBA) indépendamment de l'application concernée. De plus, l'Assistant Empaquetage ne peut pas empaqueter des applications de workflow pour les projets Microsoft® Exchange Server ou de tableau de bord interactif.
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