Demonstrations of Color Perception and the Importance of Contours

1997 ◽  
Vol 24 (4) ◽  
pp. 267-268 ◽  
Author(s):  
David T. Horner
Keyword(s):  
Color Vision ◽  
Visual Stimuli ◽  
Color Perception ◽  
Visual Performance ◽  
Receptor Cells ◽  
Opponent Process ◽  
Process Theories ◽  
Contour Information

A series of easily and inexpensively produced demonstrations provides examples of color perception after receptor cells have adapted to a stimulus. Visual performance under these conditions reveals phenomena that theories of color vision must explain. Students report their impressions of visual stimuli, and a discussion of trichromatic and opponent-process theories follows. These phenomena generate a second series of demonstrations showing the importance of contour information for perception.

Color-blindness simulation for red-green and blue-yellow ambiguity

2021 ◽  
pp. 1-12
Author(s):  
Sheida Anbari ◽  
Hamid Reza Hamidi ◽  
Shokoh Kermanshahani
Keyword(s):  
Color Vision ◽  
Color Perception ◽  
Color Blindness ◽  
Daily Activities ◽  
Reasonable Accuracy ◽  
Simulation Performance ◽  
Normal Color Vision ◽  
Test Kit ◽  
Different Types ◽  
Color Vision Test

Color blindness has important effects on people’s daily activities, since most activities require a discernment between colors. It is very important for engineers and designers to understand how colorblind people perceive colors. Therefore, many methods have been proposed to simulate color perception of people affected by Dichromacy and anomalous Trichromacy. However, the simulation results rarely have been evaluated with the reports of concerned individuals. In first study, we tried to simulate the color perception of people with different types (red and green) and different degrees of color blindness. Different degrees of red-green deficiency is simulated on the 24-plates brand of the Ishihara color vision test kit. Then simulated plates were tested on people with normal color vision. The results show that the simulation performance is better in the case of high degrees of red-green deficiency. There is also a clear difference between the assessment of female and male volunteers. In another study, the perception of the color of people with blue-yellow blindness is also considered. The proposed blue-yellow blind simulation is compared with the result of another research project. The results show that the color perception of individuals with different degrees of blue-yellow blindness can be reconstructed with a reasonable accuracy.

scholarly journals Processing of the S-cone signals in the early visual cortex of primates

2013 ◽  
Vol 31 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Youping Xiao
Keyword(s):  
Visual Cortex ◽  
Color Vision ◽  
Short Wavelength ◽  
Nonhuman Primates ◽  
Striate Cortex ◽  
Color Perception ◽  
Visual Pathway ◽  
Visual Features ◽  
Area V2 ◽  
Early Visual Cortex

AbstractThe short-wavelength-sensitive (S) cones play an important role in color vision of primates, and may also contribute to the coding of other visual features, such as luminance and motion. The color signals carried by the S cones and other cone types are largely separated in the subcortical visual pathway. Studies on nonhuman primates or humans have suggested that these signals are combined in the striate cortex (V1) following a substantial amplification of the S-cone signals in the same area. In addition to reviewing these studies, this review describes the circuitry in V1 that may underlie the processing of the S-cone signals and the dynamics of this processing. It also relates the interaction between various cone signals in V1 to the results of some psychophysical and physiological studies on color perception, which leads to a discussion of a previous model, in which color perception is produced by a multistage processing of the cone signals. Finally, I discuss the processing of the S-cone signals in the extrastriate area V2.

scholarly journals Diverse Cell Types, Circuits, and Mechanisms for Color Vision in the Vertebrate Retina

2019 ◽  
Vol 99 (3) ◽  
pp. 1527-1573 ◽  
Author(s):  
Wallace B. Thoreson ◽  
Dennis M. Dacey
Keyword(s):  
Color Vision ◽  
Ganglion Cells ◽  
Color Perception ◽  
Visible Spectrum ◽  
Cell Types ◽  
Photon Flux ◽  
Low Light ◽  
Vertebrate Retina ◽  
Light Levels ◽  
Synaptic Interactions

Synaptic interactions to extract information about wavelength, and thus color, begin in the vertebrate retina with three classes of light-sensitive cells: rod photoreceptors at low light levels, multiple types of cone photoreceptors that vary in spectral sensitivity, and intrinsically photosensitive ganglion cells that contain the photopigment melanopsin. When isolated from its neighbors, a photoreceptor confounds photon flux with wavelength and so by itself provides no information about color. The retina has evolved elaborate color opponent circuitry for extracting wavelength information by comparing the activities of different photoreceptor types broadly tuned to different parts of the visible spectrum. We review studies concerning the circuit mechanisms mediating opponent interactions in a range of species, from tetrachromatic fish with diverse color opponent cell types to common dichromatic mammals where cone opponency is restricted to a subset of specialized circuits. Distinct among mammals, primates have reinvented trichromatic color vision using novel strategies to incorporate evolution of an additional photopigment gene into the foveal structure and circuitry that supports high-resolution vision. Color vision is absent at scotopic light levels when only rods are active, but rods interact with cone signals to influence color perception at mesopic light levels. Recent evidence suggests melanopsin-mediated signals, which have been identified as a substrate for setting circadian rhythms, may also influence color perception. We consider circuits that may mediate these interactions. While cone opponency is a relatively simple neural computation, it has been implemented in vertebrates by diverse neural mechanisms that are not yet fully understood.

scholarly journals Variations in normal color vision. V. Simulations of adaptation to natural color environments

2009 ◽  
Vol 26 (1) ◽  
pp. 133-145 ◽  
Author(s):  
IGOR JURICEVIC ◽  
MICHAEL A. WEBSTER
Keyword(s):  
Color Vision ◽  
Color Perception ◽  
Color Appearance ◽  
Normal Color Vision ◽  
Natural Color ◽  
Outdoor Scenes ◽  
Different Seasons ◽  
Spectral Statistics ◽  
Unique Hues ◽  
Different Color

AbstractModern accounts of color appearance differ in whether they assume that the perceptual primaries (e.g., white and the unique hues of red, green, blue, and yellow) correspond to unique states determined by the spectral sensitivities of the observer or by the spectral statistics of the environment. We examined the interaction between observers and their environments by asking how color perception should vary if appearance depends on fixed responses in a set of color channels, when the sensitivities of these channels are adapted in plausible ways to different environments. Adaptation was modeled as gain changes in the cones and in multiple postreceptoral channels tuned to different directions in color–luminance space. Gains were adjusted so that the average channel responses were equated across two environments or for the same environment during different seasons, based on sets of natural outdoor scenes (Webster et al., 2007). Because of adaptation, even observers with a shared underlying physiology should perceive color in significantly and systematically different ways when they are exposed to and thus adapted by different contexts. These include differences in achromatic settings (owing to variations in the average chromaticity of locations) and differences in perceived hue (because of differences in scene contrasts). Modeling these changes provides a way of simulating how colors might be experienced by individuals in different color environments and provides a measure of how much color appearance might be modulated for a given observer by variations in the environment.

scholarly journals Foraging Small White Butterflies, Pieris rapae, Search Flowers Using Color Vision

2021 ◽  
Vol 9 ◽  
Author(s):  
Kentaro Arikawa ◽  
Yoshihiro Nakatani ◽  
Hisaharu Koshitaka ◽  
Michiyo Kinoshita
Keyword(s):  
Feeding Behavior ◽  
Color Vision ◽  
Pieris Rapae ◽  
Sucrose Solution ◽  
Action Spectrum ◽  
Visual Stimuli ◽  
Behavioral Experiments ◽  
True Color ◽  
Flower Preference ◽  
Colored Disk

We demonstrate that the small white butterfly, Pieris rapae, uses color vision when searching flowers for foraging. We first trained newly emerged butterflies in a series of indoor behavioral experiments to take sucrose solution on paper disks, colored either blue, green, yellow, or red. After confirming that the butterflies were trained to visit a certain colored disk, we presented all disks simultaneously. The butterflies selected the disk of trained color, even among an array of disks with different shades of gray. We performed the training using monochromatic lights and measured the action spectrum of the feeding behavior to determine the targets’ Pieris-subjective brightness. We used the subjective brightness information to evaluate the behavioral results and concluded that Pieris rapae butterflies discriminate visual stimuli based on the chromatic content independent of the intensity: they have true color vision. We also found that Pieris butterflies innately prefer blue and yellow disks, which appears to match with their flower preference in the field, at least in part.

scholarly journals Demands of Geometry on Color Vision

2016 ◽  
Author(s):  
Dale Purves ◽  
Chidambaram Yegappan
Keyword(s):  
Color Vision ◽  
Color Perception ◽  
Geometrical Analysis

The reasons for the circular sense of human color perception generated by two sorts of color opponent neurons and three cone types are not well understood. Here we use geometrical analysis to examine the hypothesis that opponency, the recursive nature of color perception, and trichromacy arise as the most efficient ways of distinguishing spectrally different points on a plane using a minimum of color classes and receptor types.

scholarly journals Color Perception in Protanomalous Female Macaca fascicularis

i-Perception ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 204166951984613 ◽  
Author(s):  
Kanthi A. Widayati ◽  
Atsuko Saito ◽  
Bambang Suryobroto ◽  
Akichika Mikami ◽  
Kowa Koida
Keyword(s):  
Animal Model ◽  
Color Vision ◽  
X Chromosome ◽  
Macaca Fascicularis ◽  
Color Perception ◽  
Color Vision Deficiency ◽  
Macaque Monkeys ◽  
Color Pair

Protanomalous females with X chromosome-linked color vision deficiency exhibit mild abnormalities, whereas dichromats show a distinct deficiency in discriminating certain color pairs. Dichromats have an advantage in detecting a textured target when it is camouflaged by red-green colors, owing to their insensitivity to these colors. However, it is not certain whether protanomalous females possess a similar advantage in breaking camouflage. Here, we introduce an animal model of dichromatic macaque monkeys and protanomalous females. We examined whether protanomalous females have the same advantage in breaking color camouflage as shown by dichromatic macaques. We also tested whether they could discriminate a certain color pair that trichromats could, where the dichromats are confused. Our experiments show that protanomalous macaques can break color camouflage, similar to dichromats, and can discriminate colors similarly to trichromats. Protanomalous females are thus thought to have the combined ecological advantages of being both trichromats and dichromats.

scholarly journals Color vision in ADHD: Part 2 - Does Attention influence Color Perception?

2014 ◽  
Vol 10 (1) ◽  
pp. 39 ◽  
Author(s):  
Soyeon Kim ◽  
Mohamed Al-Haj ◽  
Stuart Fuller ◽  
Samantha Chen ◽  
Umesh Jain ◽  
...  
Keyword(s):  
Color Vision ◽  
Color Perception
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