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A color code is a system for encoding and representing non-color information with colors to facilitate communication. This information tends to be categorical though may also be sequential.
Color blindness or color vision deficiency (CVD) is the decreased ability to see color or differences in color. The severity of color blindness ranges from mostly unnoticeable to full absence of color perception. Color blindness is usually an inherited problem or variation in the functionality of one or more of the three classes of cone cells in the retina, which mediate color vision. The most common form is caused by a genetic condition called congenital red–green color blindness, which affects up to 1 in 12 males (8%) and 1 in 200 females (0.5%). The condition is more prevalent in males, because the opsin genes responsible are located on the X chromosome. Rarer genetic conditions causing color blindness include congenital blue–yellow color blindness, blue cone monochromacy, and achromatopsia. Color blindness can also result from physical or chemical damage to the eye, the optic nerve, parts of the brain, or from medication toxicity. Color vision also naturally degrades in old age.
A set of primary colors or primary colours consists of colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of a broad range of colors in, e.g., electronic displays, color printing, and paintings. Perceptions associated with a given combination of primary colors can be predicted by an appropriate mixing model that reflects the physics of how light interacts with physical media, and ultimately the retina.
The Ishihara test is a color vision test for detection of red-green color deficiencies. It was named after its designer, Shinobu Ishihara, a professor at the University of Tokyo, who first published his tests in 1917.
Color constancy is an example of subjective constancy and a feature of the human color perception system which ensures that the perceived color of objects remains relatively constant under varying illumination conditions. A green apple for instance looks green to us at midday, when the main illumination is white sunlight, and also at sunset, when the main illumination is red. This helps us identify objects.
The CIELAB color space, also referred to as L*a*b*, is a color space defined by the International Commission on Illumination in 1976. It expresses color as three values: L* for perceptual lightness and a* and b* for the four unique colors of human vision: red, green, blue and yellow. CIELAB was intended as a perceptually uniform space, where a given numerical change corresponds to a similar perceived change in color. While the LAB space is not truly perceptually uniform, it nevertheless is useful in industry for detecting small differences in color.
Dichromacy is the state of having two types of functioning photoreceptors, called cone cells, in the eyes. Organisms with dichromacy are called dichromats. Dichromats require only two primary colors to be able to represent their visible gamut. By comparison, trichromats need three primary colors, and tetrachromats need four. Likewise, every color in a dichromat's gamut can be evoked with monochromatic light. By comparison, every color in a trichromat's gamut can be evoked with a combination of monochromatic light and white light.
A color wheel or color circle is an abstract illustrative organization of color hues around a circle, which shows the relationships between primary colors, secondary colors, tertiary colors etc.
A color rendering index (CRI) is a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with a natural or standard light source. Light sources with a high CRI are desirable in color-critical applications such as neonatal care and art restoration.
In photography and image processing, color balance is the global adjustment of the intensities of the colors. An important goal of this adjustment is to render specific colors – particularly neutral colors like white or grey – correctly. Hence, the general method is sometimes called gray balance, neutral balance, or white balance. Color balance changes the overall mixture of colors in an image and is used for color correction. Generalized versions of color balance are used to correct colors other than neutrals or to deliberately change them for effect. White balance is one of the most common kinds of balancing, and is when colors are adjusted to make a white object appear white and not a shade of any other colour.
An anomaloscope is an instrument and color vision test, often used to quantify and characterize color blindness. They are expensive and require specialized knowledge to operate, but are viewed as the gold standard for color vision standards. As a result, they are normally used for academic studies, rather than job pre-screening. They are also used to validate other color vision standards with regards to classification of color vision defects.
The Farnsworth–Munsell 100 Hue Color Vision test is a color vision test often used to test for color blindness. The system was developed by Dean Farnsworth in the 1940s and it tests the ability to isolate and arrange minute differences in various color targets with constant value and chroma that cover all the visual hues described by the Munsell color system. There are several variations of the test, one featuring 100 color hues and one featuring 15 color hues. Originally taken in an analog environment with physical hue tiles, the test is now taken from computer consoles. An accurate quantification of color vision accuracy is particularly important to designers, photographers and colorists, who all rely on accurate color vision to produce quality content.
EnChroma lenses are specialized glasses designed to address symptoms of red-green color blindness. Studies have shown that these lenses can alter the perception of colors that were already perceived, but they do not restore normal color vision.
The City University test is a color vision test used to detect color vision deficiency. The commonly used Ishihara test is used to detect mainly congenital red-green color blindness, but its usefulness is limited in detecting acquired color vision deficiencies.
Data visualization involves presenting data and information using visual elements like charts, graphs, and maps. It simplifies complex data, making patterns and trends more apparent, and aiding in better understanding and decision-making. And color coding in data visualization is implemented to help users of data to easily read, understand, and categorize the different facets of information that a given set data is trying to explain.
A color vision test is used for measuring color vision against a standard. These tests are most often used to diagnose color vision deficiencies, though several of the standards are designed to categorize normal color vision into sub-levels. With the large prevalence of color vision deficiencies and the wide range of professions that restrict hiring the colorblind for safety or aesthetic reasons, clinical color vision standards must be designed to be fast and simple to implement. Color vision standards for academic use trade speed and simplicity for accuracy and precision.
Color blind glasses or color correcting lenses are light filters, usually in the form of glasses or contact lenses, that attempt to alleviate color blindness, by bringing deficient color vision closer to normal color vision or to make certain color tasks easier to accomplish. Despite its viral status, the academic literature is generally skeptical of the efficacy of color correcting lenses.
Color tasks are tasks that involve the recognition of colors. Color tasks can be classified according to how the color is interpreted. Cole describes four categories of color tasks:
Congenital red–green color blindness is an inherited condition that is the root cause of the majority of cases of color blindness. It has no significant symptoms aside from its minor to moderate effect on color vision. It is caused by variation in the functionality of the red and/or green opsin proteins, which are the photosensitive pigment in the cone cells of the retina, which mediate color vision. Males are more likely to inherit red–green color blindness than females, because the genes for the relevant opsins are on the X chromosome. Screening for congenital red–green color blindness is typically performed with the Ishihara or similar color vision test. There is no cure for color blindness.
Holmgren's wool test also known as Holmgren's colored wool test is a color vision test used to detect color vision deficiency. Swedish physiologist Frithiof Holmgren introduced the test in 1874. It was the first successful attempt to standardize the detection of color blindness. William Thomson simplified the original Holmgren test, and later named as Holmgren-Thomson test.
References
- ↑ Laxar, K. V. (1998). "U.S. Navy Color Vision Standards Revisited". Groton, Connecticut: Naval Submarine Medical Research Lab. doi:10.21236/ada347110.
{{cite journal}}: Cite journal requires|journal=(help) - ↑ Rings, M. C. (2014). "Validation of a Computerized Color Vision Test". Pensacola, FL: Naval Aerospace Medical Institute.
{{cite journal}}: Cite journal requires|journal=(help) - ↑ "Collision With Trees on Final Approach, Federal Express Flight 1478, Boeing 727-232, N497FE, Tallahassee, Florida, July 26, 2002" (PDF). National Transportation Safety Board. 2004-06-08. NTSB/AAR-04/02. Retrieved 2019-05-29.
