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Results 401 - 450 of 1224
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Fudouzi Hiroshi - - 2006
This article describes an elastic silicone sheet with reversible tuning structural color. The sheet has a thin layer of cubic close-packed, ccp, colloidal particles embedded in poly(dimethylsiloxane), PDMS, elastomer. The array of ccp (111) planes diffracts light of selective wavelengths according to Bragg's law. This is responsible for the structural ...
Hsieh P-J - - 2006
Stimulus attributes that influence a recently reported illusion called "illusory rebound motion" (IRM; [Hsieh, P.-J., Caplovitz, G. P., & Tse, P. U. (2005). Illusory rebound motion and the motion continuity heuristic. Vision Research, 45, 2972-2985.]) are described. When a bar alternates between two different colors, IRM can be observed to ...
Wollschläger Daniel - - 2006
Dynamic texture spreading is a filling-in phenomenon where a colored pattern perceptually spreads onto an area confined by virtual contours in a multi-aperture motion display. The spreading effect is qualitatively similar to static texture spreading but widely surpasses it in strength, making it particularly suited for quantitative studies of visual ...
Ramachandran Vilayanur S - - 2006
Synesthesia is a condition in which certain otherwise normal individuals see colors when they hear tones, or, when they look at black-and-white numbers, each number is tinged with a specific color (eg 5 is red and 2 is green). We constructed a display in which a random matrix of 5s ...
Fulvio Jacqueline M - - 2006
We investigated how achromatic and chromatic cues interact to produce transparency. Observers were shown six-region stimulus displays similar to those used by R. Kasrai and F. A. A. Kingdom (2001) and made adjustments of the color and luminance attributes of one of the filter regions to achieve the best percept ...
Lewis Alex - - 2006
We investigate how the amount of information about colors in natural scenes available to the visual system depends on the spectral sensitivities of the three types of cones. We find that if we do not consider spatial information and low signal-to-noise situations, human cone spectral sensitivity curves do not provide ...
Devinck Frédéric F Section of Neurobiology, Physiology and Behavior, Department of Ophthalmology and Vision Science, University of California, Davis, 4860 Y Street, Suite 2400, Sacramento, CA 95817, USA. - - 2006
Color assimilation with bichromatic contours was quantified for spatial extents ranging from von Bezold-type color assimilation to the watercolor effect. The magnitude and direction of assimilative hue change was measured as a function of the width of a rectangular stimulus. Assimilation was quantified by hue cancellation. Large hue shifts were ...
Gordon James - - 2006
A gray region can be made to look colored by a colored surround. This phenomenon, chromatic induction, depends on color differences around the boundary of the region. We performed experiments on chromatic induction with small, initially achromatic, targets on nine different colored surrounds ranging in color from blue to red. ...
Kanai Ryota - - 2006
Perceived color at a point in space is not determined simply by the color directly stimulating the corresponding retinal position. Surface color is informed by flanking edge signals, which also serve to inhibit the intrusion of signals from neighboring surfaces. Spatially continuous local interactions among color and luminance signals have ...
Petzold Axel - - 2006
The use of spectrophotometry for the analysis of the cerebrospinal fluid (CSF) is reviewed. The clinically relevant CSF pigments--oxyhemoglobin and bilirubin--are introduced and discussed with regard to clinical differential diagnosis and potentially confounding variables (the four T's: traumatic tap, timing, total protein, and total bilirubin). The practical laboratory aspects of ...
Vladusich Tony - - 2006
How do induced brightness and darkness signals from local and remote surfaces interact to determine the final achromatic color percept of a target surface? An emerging theory of achromatic color perception posits that brightness and darkness percepts are computed by weighting and summing the induction signals generated at edges in ...
Billock Vincent A - - 2006
Fechner-Benham subjective color is widely believed to be governed by local interactions in early (probably retinal) mechanisms. Here we report three lines of phenomenological evidence that suggest otherwise: subjective colors seen in spatially extended stimuli (a) are dependent on global aspects of the stimuli; (b) can become multistable in position; ...
Anderson Stephen D - - 2006
Surgeons using a fresh tissue dissection laboratory need specimens with tissue color and texture as close as possible to those of a living body. Completely unembalmed specimens kept in a cooler remain in good condition only for a few days, and then decay rapidly. Unembalmed specimens can be frozen for ...
Bonato Frederick - - 2006
The effects of visual field color and spatial complexity on self-motion perception were investigated by placing observers inside a large rotating cylinder (optokinetic drum). Under optokinetic-drum conditions visually induced self-motion (vection) is typically perceived within 30 s, even though all forms of sensory input (eg vestibular, proprioceptive, auditory), except vision, ...
Linares Daniel - - 2006
When a stimulus repeatedly and rapidly changes color (e.g., between red and green) and motion direction (e.g., upwards and downwards) with the same frequency, it was found that observers were most likely to pair colors and motion directions when the direction changes lead the color changes by approximately 80 ms. ...
Mizokami Yoko Y Department of Psychology, University of Nevada, Reno, Reno, NV 89557, - - 2006
Most wavelengths change hue when mixed with white light. These changes, known as the Abney effect, have been extensively studied to characterize nonlinearities in the neural coding of color, but their potential function remains obscure. We measured the Abney effect in a new way--by varying the bandwidth of the spectrum ...
Webster Michael A - - 2006
The perception of blur in images can be strongly affected by prior adaptation to blurry images or by spatial induction from blurred surrounds. These contextual effects may play a role in calibrating visual responses for the spatial structure of luminance variations in images. We asked whether similar adjustments might also ...
Katzner Steffen - - 2006
In four variants of a speeded target detection task, we investigated the processing of color and motion signals in the human visual system. Participants were required to attend to both a particular color and direction of motion in moving random dot patterns (RDPs) and to report the appearance of the ...
Logvinenko Alexander D - - 2006
In asymmetric lightness matching tasks, observers sometimes report that they cannot achieve satisfactory matches between achromatic surfaces under different neutral illuminants. The surfaces appear different, yet no further adjustment of either surface improves the match. There are evident difficulties in interpreting data from a task that the observer cannot always ...
Soranzo Alessandro - - 2006
It has been shown that lightness constancy depends on the articulation of the visual field (Agostini & Galmonte, 1999). However, among researchers there is little agreement about the meaning of "articulation." Beyond the terminological heterogeneity, an important issue remains: What factors are relevant for the stability of surface color perception? ...
Forte Jason D - - 2006
We measured responses to red-green color variation in parvocellular (PC) neurons in the lateral geniculate nucleus of dichromatic ("red-green color blind") marmoset monkeys. Although these animals lack distinct visual pigments to distinguish between wavelengths in this range, many of the colored stimuli nevertheless produced robust responses in PC cells. We ...
Von der Heydt Rüdiger R Department of Neuroscience and Krieger Mind/Brain Institute, 338 Krieger Hall, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21210, USA. - - 2006
Two phenomena can be observed in the watercolor illusion: illusory color spreading and figure-ground organization. We performed experiments to determine whether the figure-ground effect is a consequence of the color illusion or due to an independent mechanism. Subjects were tested with displays consisting of six adjacent compartments--three that generated the ...
Kehoe David M - - 2006
The acclimation of photosynthetic organisms to changes in light color is ubiquitous and may be best illustrated by the colorful process of complementary chromatic adaptation (CCA). During CCA, cyanobacterial cells change from brick red to bright blue green, depending on their light color environment. The apparent simplicity of this spectacular, ...
Wiles Janet - - 2006
Human perception is finely tuned to extract structure about the 4D world of time and space as well as properties such as color and texture. Developing intuitions about spatial structure beyond 4D requires exploiting other perceptual and cognitive abilities. One of the most natural ways to explore complex spaces is ...
Gomes Ursula R - - 2005
Large-field trichromacy is a general feature of protanope and deuteranope humans, provided that the stimuli size extends to an 8 degrees visual angle. In this study we compared the performance of five male and three female tufted capuchin monkeys (Cebus apella) in discriminating pairs of Munsell color papers. Human subjects ...
Mureika J R - - 2005
The fractal dimensions of color-specific paint patterns in various Jackson Pollock paintings are calculated using a filtering process that models perceptual response to color differences (L*a*b* color space). The advantage of the L*a*b* space filtering method over traditional red-green-blue (RGB) spaces is that the former is a perceptually uniform (metric) ...
Lotto R Beau - - 2005
Bees, like humans, can continue to see a surface from its color even when the scene's global illuminant changes (which is a phenomenon called color constancy). It is not known, however, whether they can also generate color-constant behavior in more natural complex scenes that are lit by multiple lights simultaneously, ...
Locke B - - 2005
Fading of artificial hair color has been investigated by simulating actual usage conditions through exposure to artificial radiation in a weatherometer, with 0.35 mW/(m(2) nm) at 340 nm, for 16 to 48 hours, and by periodical washing. Hair color was produced by using commercial two-part, permanent hair dyes with light ...
Wood Joanne M - - 2005
PURPOSE: Red signals are typically used to signify danger. This study was conducted to investigate a situation identified by train drivers in which red signals appear yellow when viewed at long distances (approximately 900 m) through progressive-addition lenses. METHODS: A laboratory study was conducted to investigate the effects of defocus, ...
Bimler David L - - 2005
Luminance-dependent change in color appearance--the Bezold-Brücke effect--was investigated in protanopes and related to that in normal trichromats. Spectral lights were presented at six luminance levels covering mesopic, low, and high photopic vision-across three log steps from 0.76 to 760 Td. To judge color appearance, a variant of the color-naming method ...
Hillis James M - - 2005
Color vision is useful for detecting surface boundaries and identifying objects. Are the signals used to perform these two functions processed by common mechanisms, or has the visual system optimized its processing separately for each task? We measured the effect of mean chromaticity and luminance on color discriminability and on ...
Drum Bruce - - 2005
We present evidence that steady achromatic adapting fields can produce response saturation in color-opponent pathways. We measured tvi (log increment threshold illuminance versus log background illuminance) functions at four test wavelengths (430, 490, 575, and 660 nm) and nine background illuminances from 4.0 to 5.6 log Td. Foveal, 2 degrees ...
Pinna Baingio - - 2005
Coloration and figural properties of neon color spreading and the watercolor illusion are studied using phenomenal and psychophysical observations. Coloration properties of both effects can be reduced to a common limiting condition, a nearby color transition called the two-dot limiting case, which clarifies their perceptual similarities and dissimilarities. The results ...
Lee Yong-Keun - - 2005
PURPOSE: To determine the difference in lightness, chroma, hue angle and color of four kinds of esthetic restorative materials of the same shade designation by the change of standard illuminants of D65 (daylight), A (incandescent lamp) and F2 (fluorescent lamp). METHODS: Spectral reflectance and color of four resin composites, a ...
Heydecke Guido - - 2005
No soft tissue shade guide is available for matching the color of denture resins to human intraoral soft tissues. To determine the color of both the gingiva and the alveolar mucosa, intraoral soft tissue colors of 150 men and women were assessed under standardized lighting conditions. Colors of the papilla, ...
Lynch David K - - 2005
Distant objects like clouds, mountains, and the Sun can appear to have colors that are significantly different from their intrinsic colors: the low Sun is often red, white clouds and snow-capped peaks appear yellow or pink, and dark green or gray mountains can appear blue or purple. The color alteration ...
Spitzer Hedva - - 2005
The appearance of a patch of color or its contrast depends not only on the stimulus itself but also on the surrounding stimuli (induction effects-simultaneous contrast). A comprehensive computational physiological model is presented to describe chromatic adaptation of the first (retinal) and second (cortical) orders, and to predict the different ...
Sirianuntapiboon Suntud - - 2006
Studies were carried out on the growth of Chromatium sp. on seafood wastewater (SFWW), which under facultative conditions and light exposure produced red pigment. The strain grew and utilized organic matter in both dark and light exposure conditions, but it produced red pigment when exposed to light. The growth was ...
Paravina Rade D - - 2005
The aim of this study was to evaluate polymerization-dependent changes in the color and translucency parameter (TP) of resin composites and to compare results obtained using two color-difference metric formulae, CIELAB and CIEDE 2000. Twenty-eight shades of commercial resin composites were analyzed. Specimens (n = 5) were made as discs, ...
Andersson S - - 2005
Nigella degenii ssp. barbro and ssp. jenny differ from related taxa in being dimorphic for pollen color, with some plants having dark pollen and others light pollen. In this study we performed experimental crosses to determine whether the difference in pollen color is governed by few or many loci and ...
Kinoshita Shuichi - - 2005
Coloring in nature mostly comes from the inherent colors of materials, but it sometimes has a purely physical origin, such as diffraction or interference of light. The latter, called structural color or iridescence, has long been a problem of scientific interest. Recently, structural colors have attracted great interest because their ...
Shevell Steven K - - 2006
Chromatic assimilation is the shift in color appearance toward nearby light. Assimilation was measured using nearby light with time-varying chromaticity. This light induced time-varying assimilation within the test area. Assimilation was quantified by the amplitude of temporally varying test-area light--in counter-phase to the induced assimilation--required to null the assimilation. Unlike ...
Hiraga Sota - - 2005
The butterflies Graphium sarpedon nipponum Fruhstorfer and Papilio xuthus Linné show pupal protective color polymorphism, but the two species appear to have different sensory mechanisms for determining pupal coloration. When light was of sufficient illumination, the larvae of Graphium sarpedon became bright yellowish green pupae on white pupation boards and ...
Liu Li - - 2005
We consider the reproduction of color subject to material and neighborhood constraints. By "material constraints," we mean any constraints that are applied to the amount of ink, lights, voltages, and currents that are used in the generation of color. In the first instance we consider the problem of reproducing a ...
Sohmiya Seiyu - - 2005
In van Tuijl's neon configurations, an achromatic line segment on a blue inducer produces yellowish illusory color in the illusory area. This illusion has been explained based on the idea of the complementary color induced by the blue inducer. However, it is proposed here that this illusion can be also ...
Endler John A - - 2005
Animal color pattern phenotypes evolve rapidly. What influences their evolution? Because color patterns are used in communication, selection for signal efficacy, relative to the intended receiver's visual system, may explain and predict the direction of evolution. We investigated this in bowerbirds, whose color patterns consist of plumage, bower structure, and ...
Beer R Dirk - - 2005
We describe a device that can display very high intensity (up to 400,000 cd/m2), high-resolution visual stimuli. The device is inexpensive, is easily controlled by a conventional computer and video card, and can be calibrated for use in vision research or clinical applications. The display is capable of presenting highly ...
Becker Cordula - - 2006
Our understanding of human visual perception generally rests on the assumption that conscious visual states represent the interaction of spatial structures in the environment and our nervous system. This assumption is questioned by circumstances where conscious visual states can be triggered by external stimulation which is not primarily spatially defined. ...
Coch Donna - - 2005
Stimuli designed to selectively elicit motion or color processing were used in a developmental event-related potential study with adults and children aged 6, 7 and 8. A positivity at posterior site INZ (P-INZ) was greater to motion stimuli only in adults. The P1 and N1 were larger to color stimuli ...
Katsuura Tetsuo - - 2005
This article presents our recent studies on the effects of color temperature on the taste sense and the influence of color temperature on bright light exposure during night rest period. Ten male Japanese and ten male Chinese were exposed to four illumination conditions (200, 1500 lx x 3000, 7500 K). ...
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