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Kuhlow B - - 1987
In a single light valve system, MTF curves and light efficiencies are calculated, which are only caused by the dark field method. Extended light sources in a regular arrangement with continuous spectral density in each of the three color channels-red, green, and blue-of the TV color projector are taken into ...
Hart W M WM - - 1987
Theories of color vision have been founded on behavioral observations of how the human eye distinguishes colors and mixtures of colors. Studies of congenital dyschromatopsias (inherited disorders of color vision) have been important to the development of these theories. Subsequent studies of acquired dyschromatopsias (disorders of color vision caused by ...
Malament K A - - 1987
The use of Dicor cast glass-ceramic material for fixed prosthodontic complete crowns has been described. The advantages of this material are chemical and physical uniformity, marginal accuracy, uncomplicated fabrication from wax-up to casting, ceramming, and coloring, ease of adjustment, excellent esthetics resulting from natural translucency, light absorption, light refraction, and ...
Painter C - - 1987
The purpose of this article is to compare aspects of the performance of three widely-used rigid laryngoscopy telescopes. The Nagashima SFT-I, Wolf 4450.57, and Karl Storz 8702 D were used with a JVC GX-N8U camera and Panasonic PV 8600 VCR to make recordings of a one-tenth-inch grid at various distances ...
Adams A J - - 1987
A generalized loss of visual sensitivity, even for foveal targets, has been reported as an early sign of glaucoma. In the present study of central vision, we used relatively simple and rapid clinical tests of color thresholds, color discrimination, and spatial contrast sensitivity to compare the vision of three age-matched ...
Uchikawa K - - 1987
Wavelength-discrimination thresholds were measured with stimulus durations of 8, 500, and 2000 msec for test wavelengths of 420 to 630 nm at equal luminance of 100 Td. With the short duration of 8 msec, the discrimination thresholds increased for most wavelengths, but they decreased for the wavelengths near 460 nm. ...
Ronchi L R - - 1987
An investigation into the stability of color appreciation after repeated testing with a light emitting diode (LED) system was undertaken. Experienced subjects viewed a LED simplon that had been set at a plateau intensity (in the photometric range), the principal variation being pulse duration (16 to 320 ms). A forced-choice ...
Felleman D J - - 1987
Receptive field properties of 147 neurons histologically verified to be located in area V3 were investigated during semichronic recording from paralyzed anesthetized macaque monkeys. Quantitative analyses were made of neuron selectivities for direction, orientation, speed, binocular disparity, and color. The majority of neurons in V3 (76%) were strongly orientation selective; ...
Lucchitta B K - - 1987
The evidence for volcanism on Mars is commonly accepted, but none has been documented in the Valles Marineris equatorial rift system. A recent survey of the troughs in this valley revealed dark patches that are interpreted to be volcanic vents. The configuration and association of these patches with tectonic structures ...
Savage A - - 1987
Old World monkeys and apes have been reported to differ from New World monkeys in their abilities to discriminate colors across the visible spectrum. Old World monkeys and apes (Macaca, Pan, Pongo) discriminate colors quite accurately, while some New World monkeys studied (Saimiri, Cebus) have shown lower sensitivity to and ...
Mitsuboshi M - - 1987
The critical durations for temporal integration at threshold were obtained for lights of various wavelengths, presented both against darkness and against achromatic or chromatic backgrounds of different luminances. The critical duration (tc) was defined by a point of intersection of the two lines with the slopes of zero and unity ...
Arnold K - - 1987
Wavelength discrimination was measured with two individuals using a behavioral training technique. The delta lambda function has three minima, indicating best discrimination at 400, 510 and at 570 nm (S2) or 600 nm (S1). In the range between 450 and 510 nm the ability to discriminate wavelengths was absent. This ...
Alpern M - - 1987
Differences between W.D.W. chromaticities of monochromatic lights obtained with all colorimeter beams incident on the retina "off-axis" and those found for lights striking the retina normally have been studied throughout the visible spectrum on 4 normal trichromats. The results are inconsistent with: (i) the assumption in Weale's theories of the ...
Vimal R L - - 1987
An interocular matching technique was used to investigate the variation of chromaticity and brightness following steady viewing of a chromatic test light (identical adapting and testing color). Adaptation times were of sufficient duration to ensure stable matches. Following chromatic adaptation we found changes in hue, saturation and brightness. The spectral ...
Nagy A L - - 1987
Rayleigh color match ranges obtained from color deficient observers varied considerably as a function of spatial and temporal parameters of stimulus presentation. The results suggest that color discrimination losses in color deficients result from abnormalities in the spatial and temporal properties of neural coding in addition to cone photopigment abnormalities.
Korth M - - 1987
The pattern-evoked electroretinogram (PERG) was studied in response to square-wave stripe patterns contrasting either between dark and colored stripes ("red-black" or "green-black" luminance contrast pattern) or between the two colors (red-green chromatic contrast pattern). All lights were matched in photopic luminance. A two-channel Maxwellian view system was used to present ...
Jacobs G H - - 1987
The color vision of five saddle-backed tamarins (Saguinus fuscicollis) was studied. Behavioral tests of color discrimination and spectral sensitivity indicate that this species has a color vision polymorphism. Individual monkeys have either dichromatic or trichromatic color vision. Measurements of the spectral sensitivity of cones on this species were made on ...
Mitsuboshi M - - 1987
The present study demonstrated that the temporal integration time (t.i.t.) could be prolonged even if the background energy was increased, provided that the background consisted of the colors opponent to each other. This was found, more or less, irrespective of the test stimulus size. These results suggest that the t.i.t. ...
Pickering A D - - 1986
Adaptation of brown trout to a black or white background had no statistically significant influence on the activity of the pituitary-interrenal axis in unstressed fish, in fish under conditions of mild chronic stress, or in fish under conditions of severe, acute stress. This finding is in contrast to several other ...
Okelo O - - 1986
Color changes in Chameleo gracilis are under neuroendocrine control. Denervation of the limbs, by removal of the sciatic or brachial nerves, does not interfere with the normal color changes in the affected limbs. Denervated skins, placed back onto C. gracilis, show color changes in synchrony with the rest of the ...
Benzschawel T - - 1986
We examined the effects of probing human color mechanisms using sinusoidal spectral power distributions (SPD's) varying in frequency (i.e., from 0.1 to 5.0 cycles/300 nm for a constant starting phase) and phase (i.e., from 0 to 360 deg for a fixed frequency of 1 cycle/300 nm) through computer simulation using ...
Krauskopf J - - 1986
A new method of measuring simultaneous contrast, or chromatic induction, is introduced and used to test the hypotheses that induction results from either multiplicative or subtractive interaction of either like receptors or like second-stage, opponent mechanisms. Predictions derived from these hypotheses do not predict the outcome of the experiments as ...
Hurlbert A - - 1986
The computational problem underlying color vision is to recover the invariant surface-spectral-reflectance properties of an object. Lightness algorithms, which recover an approximation to surface reflectance in independent wavelength channels, have been proposed as one method to compute color. This paper clarifies and formalizes the lightness problem by proposing a new ...
D'Zmura M - - 1986
We develop a model of how the visual system finds the colors of objects that have unknown shapes and positions. The model relies on mechanisms of light adaptation, coupled with eye movements, to recover three descriptors of surface reflectance that are represented in the signals of an achromatic mechanism and ...
Arend L - - 1986
Observers matched patches (simulated Munsell papers) in two simultaneously presented computer-controlled displays, a standard array presented under 6500-K illumination and a test array under 4000 or 10,000 K. Adaptation to the test illuminants was limited. The adjusted patch was surrounded by a single color (annulus display) or by many colors ...
Bradley A - - 1986
Using isochromatic luminance gratings and isoluminant red-green color gratings, examined luminance and color discrimination in amblyopia were examined. Complete color and luminance contrast sensitivity functions were measured monocularly from each eye of six normal and six amblyopic observers. Similar spatial frequency-specific color and luminance discrimination deficits were found in five ...
Hita E - - 1986
The differential chromaticity thresholds obtained by varying degrees of metamerism have been evaluated for five target chromaticities. Differences have been found between the chromaticities predicted by the CIE-1931 standard observer and those actually observed under our experimental conditions, with foveal fields of 3 degrees, luminance within the low photopic level, ...
Burkhalter A - - 1986
The responses of single cells to light bars of different orientation, direction of motion, speed, binocular disparity, and wavelength were systematically analyzed in areas V2 and VP of ventral extrastriate visual cortex in the macaque monkey. Selectivity for each of these parameters was assessed quantitatively using computer-controlled procedures. In both ...
Stanton M L - - 1986
Because availability of resources often limits seed or fruit set, increased visits by pollinators may not always lead to increases in maternal reproduction. This observation has led evolutionary biologists to hypothesize that a plant's ability to attract pollinators may have its primary impact on male fitness achieved through the fertlization ...
Neri D F - - 1986
Our purpose was to reveal the effects of ambient illumination color and various foreground/background color pairings on a choice reaction time task performed on a color CRT. Six men and two women with normal color vision served as observers in a four-alternative forced choice procedure. A small (18' visual angle) ...
Houck M R - - 1986
According to feature-integration theory (Treisman & Gelade, 1980), separable features such as color and shape exist in separate maps in preattentive vision and can be integrated only through the use of spatial attention. Many perceptual aftereffects, however, which are also assumed to reflect the features available in preattentive vision, are ...
McBrien N A - - 1986
The effect of changes of fixation target color and detail on objective refraction were assessed using the Canon Autoref R-1. In addition, the effect of ambient illumination on objective refractive results for various color fixation targets was studied. The results show that any differences induced in emmetropic observers by different ...
Johnson M A - - 1986
Until recently, color vision in the peripheral field has been thought to be substantially less developed than color vision in the central field. Although the exact dimensions vary from study to study, most estimates of peripheral chromatic perception place the limit of trichromatic vision at no more than 30 degrees ...
Cooper B A - - 1986
Empirical evidence suggests that the functional level of the institutionalized elderly is favorably affected by enriching the environment with the specific use of color and light. Evidence of the validity of this supposition would form a worthwhile contribution to geriatric rehabilitation by promoting the independence of the elderly in the ...
Krauskopf J - - 1986
Evidence supporting the existence of higher order color mechanisms, that is, ones beyond the previously identified second stage mechanisms is presented. This evidence includes a reanalysis of the data of Krauskopf et al. [Vision Res. 20, 1123-1131 (1982)] on the desensitizing effects of viewing chromatically modulated fields, new experiments on ...
Uchikawa K - - 1986
Successive and simultaneous brightness comparisons between test colors and a comparison white were performed to study how accurately the brightness of colored lights was maintained in memory. The test colors were monochromatic lights chosen from 410 to 670 nm and a white light. The stimulus duration was 1 sec, and ...
Johnson D - - 1986
A simple, relatively inexpensive technique for adequate stimulation of the visual system is described. A combination of continuous interference filters and light fibers in one compact instrument allows individual stimulation of the color channels with narrow band light in mosaic or homogeneous compositions. Effectively all parameters of stimulation may be ...
De Valois R L - - 1986
With a matching procedure, we studied the temporal properties of direct brightness (or lightness) and chromatic changes (produced by modulation of the region being matched) and induced brightness and chromatic changes (produced by modulation of the surround of the region being matched). The amount of direct brightness and color change ...
Sellers K L - - 1986
A color television display was used to measure thresholds for mixtures of red and green on a white background; red and green components could be either incremental, decremental or zero. Ellipses are fitted to a plot of green contrast as a function of red contrast, and it is argued that ...
Krauskopf J - - 1986
Viewing of annuli modulated in color in a sawtooth fashion in time results in differential threshold elevations for the detection of color changes of inscribed disks. The elevations are of nearly the same magnitude as those resulting from viewing modulated disks. However, the differential effects on thresholds for complimentary colors ...
Pugh E N EN - - 1986
The origins, development, and status of the pi mechanism theory are reviewed. The paper is divided into four sections. In the first section Stiles's general ideas about 'color mechanisms' are examined, and it is concluded that foremost amongst these is a mathematical theory that specifies certain formal rules or laws ...
Chioran G M - - 1985
A color television display can be used to determine color and brightness discrimination thresholds using identical adaptation conditions and experimental technique. The color discrimination threshold is measured by using an equiluminous test spot--i.e. one which differs in color from the surrounding screen but has the same luminance. Because there is ...
Hart W M WM - - 1985
Color contrast perimetry was used to evaluate central visual field defects in a group of 28 patients with visual loss resulting from optic nerve or retinal diseases. Kinetic perimetry was performed using colored test objects of constant luminance, equated to a white surround of 10 ft lamberts. Colored test objects ...
Palmer D A - - 1985
Twenty-four observers matched monochromatic lights to a white reference light in a 10 degree field. The retinal illuminance was 1000 Td over most of the spectrum. Twelve persons' visibility curves were more or less additive and resembled the y10 color-matching function of the CIE. Eight others had a double-peaked function, ...
Fox W - - 1985
The purpose of the studies reported herein was to determine whether the depressing effects on growth rate of dominant white (I) and recessive white (c/c) are additive or possibly interact with each other. A synthetic stock was used that was segregating for both dominant white and recessive white. Using phenotypic ...
Ward F E - - 1985
The purpose of our research was to investigate color discrimination under conditions of ambient illumination that may reduce CRT display saturation and contrast. Our research measured both the variability of color matching and the offsets from a match necessary for a 100% discrimination difference. We did this for four dominant ...
Russell P W - - 1985
Thirty-five diabetic patients who had undergone pan-retinal photocoagulation were surveyed to determine the frequency and severity of visual difficulties they experience. Among the most frequent problems were difficulty adjusting to dim lighting, difficulty adjusting to bright lighting, and trouble in sorting dark colors. Judging distances, negotiating stairways, and avoiding obstacles ...
Caldwell J A - - 1985
The effects of exposure to red, white, and blue lights on time estimation and physiological indices were examined. Sixty subjects were exposed to a total of four presentation series of red, white, and blue lights. There were two phases of the experiment: a verbal estimation phase in which subjects were ...
Mitsuboshi M - - 1985
The strength of chromatic response elicited by a briefly-flashed monochromatic light, which varied in its exposure duration, was measured with the "transient cancellation method" in Experiment 1. It was found that the chromatic response of a test color depended on brightness of the test field, up to the exposures of ...
Wandell B A - - 1985
Theories of color-difference measurement provide a quantitative means for predicting whether two lights will be discriminable to an average observer. Consider the following color-measurement hypothesis. Suppose that two lights evoke responses from the color channels that we write as vectors, U and U'. The vector difference dU = U - ...
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