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Bezold–Brücke Shift
The Bezold–Brücke shift or luminance-on-hue effect is a change in hue perception as the luminance (light intensity) of a color changes. As intensity increases, the apparent hue of stimuli of a constant spectral distribution shifts towards blue, if its dominant wavelength is below around 500 nm; or yellow, if its dominant wavelength is above 500 nm. As intensity is decreased, apparent hue shifts towards red or green. The effect was noted in 1866 by physiologist Ernst Wilhelm von Brücke, and experimental investigations by physicist and meteorologist Wilhelm von Bezold were published in 1873. It was re-investigated more thoroughly by Donald McL. Purdy in 1931. Stimuli of certain wavelengths ("invariant hues") retain their apparent hue despite changes in luminance; these have similar but not quite the same wavelengths as the unique hues red, yellow, blue, and green. A similar hue shift, the Abney effect, occurs when a visual stimulus is mixed with white light. Both the Abne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color
Color (or colour in English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is the visual perception based on the electromagnetic spectrum. Though color is not an inherent property of matter, color perception is related to an object's light absorption, emission spectra, emission, Reflection (physics), reflection and Transmittance, transmission. For most humans, colors are perceived in the visible light spectrum with three types of cone cells (trichromacy). Other animals may have a different number of cone cell types or have eyes sensitive to different wavelengths, such as bees that can distinguish ultraviolet, and thus have a different color sensitivity range. Animal perception of color originates from different light wavelength or spectral sensitivity in cone cell types, which is then processed by the brain. Colors have perceived properties such as hue, colorfulness (saturation), and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue
Blue is one of the three primary colours in the RYB color model, RYB colour model (traditional colour theory), as well as in the RGB color model, RGB (additive) colour model. It lies between Violet (color), violet and cyan on the optical spectrum, spectrum of visible light. The term ''blue'' generally describes colours perceived by humans observing light with a dominant wavelength that's between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; Azure (color), azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering#Cause of the blue colour of the sky, Rayleigh scattering. An optical effect called the Tyndall effect explains Eye color#Blue, blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective. Blue has been an important colour in art and decoration since ancient t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dominant Wavelength
In color science, the dominant wavelength is a method of approximating a color's hue. Along with purity, it makes up one half of the Helmholtz coordinates. The dominant wavelength of a given color is defined to be the wavelength of monochromatic spectral light that lies on the straight line passing through the white point and the given colour in the chromaticity diagram. Determination Helmholtz coordinates The Helmholtz coordinates are a polar coordinate system for defining a 2D chromaticity plane. The circumferential coordinate is the dominant wavelength, which is analogous to hue of the HSV color space. The radial coordinate is the purity, which is analogous to saturation of the HSV color space. Color space Not all color spaces can be used for determining the dominant wavelength of a color, because in most approximately perceptually uniform color spaces (such as CIELAB, Oklab, CIECAM02, etc) two colors with the same hue can have slightly different dominant wavelengths. Unl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yellow
Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the RGB color model, used to create colors on television and computer screens, yellow is a secondary color made by combining red and green at equal intensity. Carotenoids give the characteristic yellow color to autumn leaves, corn, canaries, daffodils, and lemons, as well as egg yolks, buttercups, and bananas. They absorb light energy and protect plants from photo damage in some cases. Sunlight has a slight yellowish hue when the Sun is near the horizon, due to atmospheric scattering of shorter wavelengths (green, blue, and violet). Because it was widely available, yellow ochre pigment was one of the first colors used in art; the Lascaux cave in France has a painting of a yellow horse 17,000 years old. Ochre and orpiment pigmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green
Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combination of yellow and cyan; in the RGB color model, used on television and computer screens, it is one of the additive primary colors, along with red and blue, which are mixed in different combinations to create all other colors. By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into chemical energy. Many creatures have adapted to their green environments by taking on a green hue themselves as camouflage. Several minerals have a green color, including the emerald, which is colored green by its chromium content. During post-classical and early modern Europe, green was the color commonly associated with wealth, merchants, bankers, and the gentry, whil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernst Wilhelm Von Brücke
Ernst Wilhelm von Brücke (; 6 July 1819 – 7 January 1892) was a German physician and physiologist. He worked on the nature of cells, physiology of language, the effect of electricity on muscles, and studies of albumin. He also made significant contributions in the fields of physics, plant physiology, microscopic anatomy, and experimental physiology. He was an influential professor of Sigmund Freud. Biography He was born Ernst Wilhelm Brücke in Berlin. He graduated in medicine at the University of Berlin in 1842, and during the following year, he became a research assistant to Johannes Peter Müller. In 1845, he founded the Physikalische Gesellschaft (Physical Society) in Berlin, together with Emil Du Bois-Reymond, Hermann von Helmholtz and others, in the house of physicist Heinrich Gustav Magnus. Later on, this became known as the Deutsche Physikalische Gesellschaft (German Society of Physics). In 1846, Brücke was elected teacher of anatomy in the Akademie der Bildenden ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilhelm Von Bezold
Johann Friedrich Wilhelm von Bezold (June 21, 1837 – February 17, 1907) was a German physicist and meteorologist born in Munich, Kingdom of Bavaria. He is best known for discovering the Bezold effect and the Bezold–Brücke shift. Bezold studied mathematics and physics at the University of Munich and the University of Göttingen. He taught meteorology in Munich from 1861, becoming a professor in 1866. In 1868 he began teaching at the Technical University of Munich. In 1875, he was named a member of the Bavarian Academy of Sciences. From 1885 to 1907 director of the Prussian Institute of Meteorology at the University of Berlin. As a scientist, he was mainly interested in the physics of the atmosphere, and he contributed much to the theory of electrical storms. Bezold was one of the early researchers of atmospheric thermodynamics. He considered pseudo-adiabatic processes describing air as it is lifted, expands, cools, and eventually condenses and precipitates its water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unique Hues
Unique hue is a term used in perceptual psychology of color vision and generally applied to the purest hues of blue, green, yellow and red. The proponents of the opponent process theory believe that these hues cannot be described as a mixture of other hues, and are therefore pure, whereas all other hues are composite. The neural correlate of the unique hues are approximated by the extremes of the opponent channels in opponent process theory. In this context, unique hues are sometimes described as " psychological primaries" as they can be considered analogous to the primary colors of trichromatic color theory. Opponent process theory The concept of certain hues as 'unique' came with the introduction of opponent process theory, which Ewald Hering introduced in 1878. Hering first proposed the idea that red, green, blue, and yellow were unique hues (''"Urfarben"''), based on the concept that these colors could not be simultaneously perceived. These hues represented the extremes o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abney Effect
The Abney effect or the purity-on-hue effect is the perception, perceived hue shift that occurs when white light is additive color, added to a spectral color, monochromatic light source. The addition of white light will cause a desaturation of the monochromatic source, as perceived by the human observer. However, a less intuitive effect of the perceived Electromagnetic spectrum#Visible radiation .28light.29, white light addition is the change in the apparent hue. This hue shift is physiological rather than physical in nature. This variance of hue as a result of the addition of white light was first described by the English chemist and physicist Sir William de Wiveleslie Abney in 1909, although the date is commonly reported as 1910. A white light source can be created by the combination of red, blue, and green light. Abney demonstrated that the cause of the apparent change in hue was the red and green light that comprised this light source, and that the blue light component had ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helmholtz–Kohlrausch Effect
The Helmholtz–Kohlrausch effect (named after Hermann von Helmholtz and V. A. Kohlrausch) is a perceptual phenomenon wherein the intense saturation of spectral hue is perceived as part of the color's luminance. This brightness increase by saturation, which grows stronger as saturation increases, might better be called chromatic luminance, since "white" or achromatic luminance is the standard of comparison. It appears in both self-luminous and surface colors, although it is most pronounced in spectral (monochromatic) colors. Lightness Even when they have the same luminance, colored lights seem brighter to human observers than white light does. The way humans perceive the brightness of the lights is different for everyone. When the colors are more saturated, our eyes interpret it as the color's luminance and chroma. This makes us believe that the colors are actually brighter. An exception to this is when the human observer is red-green colorblind, they cannot distinguish the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
