Search results for "Color perception"

Reduction of red-green discrimination by dopamine D1 receptor antagonists and retinal dopamine depletion

1996

AbstractReduction of wavelength discrimination ability in the 560–640 nm range, but not in the 404–540 nm range, has been demonstrated in goldfish after intravitreal injection of D1-dopamine receptor antagonists. Intravitreal injection of the dopaminergic neurotoxin 6-OH-dopamine severely reduced wavelength discrimination ability in the 540–661 nm range within 3 days. Discrimination ability could be reconstituted by the Dl-agonist SKF 38393. Animals recovered from injection of 6-OH-dopamine within 14–16 days. No change of wavelength discrimination was induced by 6-OH-dopamine in the 461–540 nm range. We conclude that under photopic conditions dopamine modulates retinal mechanisms involved i…

Suppressive Efficacy by a Commercially Available Blue Lens on PPR in 610 Photosensitive Epilepsy Patients

2006

Purpose Photosensitivity can represent a serious problem in epilepsy patients, also because pharmacologic treatment is often ineffective. Nonpharmacologic treatment using blue sunglasses is effective and safe in controlling photosensitivity, but large series of patients have never been studied. Methods This multicenter study was conducted in 12 epilepsy centers in northern, central, southern, and insular Italy. A commercially available lens, named Z1, obtained in a previous trial, was used to test consecutively enrolled pediatric and adult epilepsy patients with photosensitivity. Only type 4 photosensitivity (photoparoxysmal response, PPR) was considered in the study. A standardized method …

Vecākā pirmsskolas vecuma bērnu krāsu uztveres sekmēšana tēlotājdarbībā pirmsskolā

2019

Darba nosaukums: Vecākā pirmsskolas vecuma bērnu krāsu uztveres sekmēšana tēlotājdarbībā pirmskolā. Pētījuma mērķis: teorijā un praksē pārbaudīt vai tēlotājdarbībā iespējams sekmēt vecākā pirmskolas vecuma bērnu krāsu uztveres attīstību. Teorētiskajā daļā apskatīts kāda ir tēlotājdarbības nozīme bērna personības vispusīgā attīstībā, ņemot vērā krāsas lielo ietekmi uz bērna un vēlāk arī uz pieauguša cilvēka emocionālo attīstību. Analizēta literatūra saistībā ar mākslas un krāsu attīstošo ietekmi. Teorētiskā daļa balstās uz D. Lambergas, L. Slavas, I. Celmiņas, M. Dobles, E.Ozola, L. Ozola, P. Antona, Ē. Antona, lekciju materiāliem no Doc.,Dr.,paed. D.Kalējas – Gasparovičas, VISC Pirmskolas i…

Optimizing colormaps with consideration for color vision deficiency to enable accurate interpretation of scientific data

2018

Color vision deficiency (CVD) affects more than 4% of the population and leads to a different visual perception of colors. Though this has been known for decades, colormaps with many colors across the visual spectra are often used to represent data, leading to the potential for misinterpretation or difficulty with interpretation by someone with this deficiency. Until the creation of the module presented here, there were no colormaps mathematically optimized for CVD using modern color appearance models. While there have been some attempts to make aesthetically pleasing or subjectively tolerable colormaps for those with CVD, our goal was to make optimized colormaps for the most accurate perce…

Nonlinearities and Adaptation of Color Vision from Sequential Principal Curves Analysis

2016

Mechanisms of human color vision are characterized by two phenomenological aspects: the system is nonlinear and adaptive to changing environments. Conventional attempts to derive these features from statistics use separate arguments for each aspect. The few statistical explanations that do consider both phenomena simultaneously follow parametric formulations based on empirical models. Therefore, it may be argued that the behavior does not come directly from the color statistics but from the convenient functional form adopted. In addition, many times the whole statistical analysis is based on simplified databases that disregard relevant physical effects in the input signal, as, for instance…

Spatio-Chromatic Adaptation via Higher-Order Canonical Correlation Analysis of Natural Images

2014

Independent component and canonical correlation analysis are two general-purpose statistical methods with wide applicability. In neuroscience, independent component analysis of chromatic natural images explains the spatio-chromatic structure of primary cortical receptive fields in terms of properties of the visual environment. Canonical correlation analysis explains similarly chromatic adaptation to different illuminations. But, as we show in this paper, neither of the two methods generalizes well to explain both spatio-chromatic processing and adaptation at the same time. We propose a statistical method which combines the desirable properties of independent component and canonical correlat…

Photoreceptors, lightness constancy and color vision.

1986

Implementations of a novel algorithm for colour constancy

1997

AbstractIn agreement with the principles of the relativistic model proposed by Creutzfeldtet al., with the photometric rule (lightness anchoring rule) and with the influence of simultaneous contrast in the appearance of a visual scene, we propose a first-stage mechanism yielding substantial colour constancy. We have defined a set of first-stage colour descriptors, and to test their utility, we have performed a simulation using a Machine Vision System (MVS). The statistical stability of the descriptors for Munsell samples under different illuminants is good.

A field test of behavioural flexibility in Zenaida doves (Zenaida aurita).

2010

7 pages; International audience; Animals' ability to adjust their behaviour when environmental conditions change can increase their likelihood of survival. Although such behavioural flexibility is regularly observed in the field, it has proven difficult to systematically quantify and predict inter-individual differences in free-living animals. We presented 24 Zenaida doves (Zenaida aurita) on 12 territories with two learning tests in their natural habitat in Barbados. The dove pairs showed high site fidelity and territoriality, allowing us to test individuals repeatedly while accounting for the effects of territorial chases and pair bonds on our learning measures. We used a foraging apparat…

Contrast sensitivity and color perception with orange and yellow intraocular lenses

2012

To evaluate contrast sensitivity function (CSF) and color vision after implantation of either orange or yellow-tinted intraocular lenses (IOLs).Fifty-six eyes of 28 cataract patients who had bilateral implantation of orange-tinted (PC440Y Orange, Ophtec), yellow-tinted (AcrySof Natural SN60AT, Alcon), or clear (AcrySof SA60AT, Alcon) IOLs were examined. Six months postoperatively, monocular CSF under photopic and mesopic (with and without glare) conditions were measured using the Functional Visual Analyzer. Color discrimination was determined with the Farnsworth-Munsell 100-Hue test.Patients implanted with orange-tinted, yellow-tinted, or clear IOLs displayed similar CSF values, with no sta…