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Lightness
Lightness is a visual perception of the luminance (L) of an object. It is often judged relative to a similarly lit object. In colorimetry and color appearance models, lightness is a prediction of how an illuminated color will appear to a standard observer. While luminance is a linear measurement of light, lightness is a linear prediction of the human perception of that light. This distinction is meaningful because human vision's lightness perception is non-linear relative to light. Doubling the quantity of light does not result in a doubling in perceived lightness, only a modest increase. The symbol for perceptual lightness is usually either J as used in CIECAM02 or L^* as used in CIELAB and CIELUV. L^* ("Lstar") is not to be confused with L as used for luminance. In some color ordering systems such as Munsell color system, Munsell, Lightness is referenced as value. Chiaroscuro and tenebrism both take advantage of dramatic contrasts of value to heighten drama in art. Artists ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HSL And HSV
HSL and HSV are the two most common cylindrical coordinate system, cylindrical-coordinate representations of points in an RGB color model. The two representations rearrange the geometry of RGB in an attempt to be more intuitive and color vision, perceptually relevant than the cartesian coordinate system, cartesian (cube) representation. Developed in the 1970s for computer graphics applications, HSL and HSV are used today in color tool, color pickers, in image editing software, and less commonly in image analysis and computer vision. HSL stands for ''hue'', ''saturation'', and ''lightness'', and is often also called HLS. HSV stands for ''hue'', ''saturation'', and ''value'', and is also often called HSB (''B'' for ''brightness''). A third model, common in computer vision applications, is HSI, for ''hue'', ''saturation'', and ''intensity''. However, while typically consistent, these definitions are not standardized, and any of these abbreviations might be used for any of these thre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightness Approximations
Lightness is a visual perception of the luminance (L) of an object. It is often judged relative to a similarly lit object. In colorimetry and color appearance models, lightness is a prediction of how an illuminated color will appear to a standard observer. While luminance is a linear measurement of light, lightness is a linear prediction of the human perception of that light. This distinction is meaningful because human vision's lightness perception is non-linear relative to light. Doubling the quantity of light does not result in a doubling in perceived lightness, only a modest increase. The symbol for perceptual lightness is usually either J as used in CIECAM02 or L^* as used in CIELAB and CIELUV. L^* ("Lstar") is not to be confused with L as used for luminance. In some color ordering systems such as Munsell, Lightness is referenced as value. Chiaroscuro and tenebrism both take advantage of dramatic contrasts of value to heighten drama in art. Artists may also employ sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HCL Color Space
HCL ( hue– chroma–luminance) or LCh refers to any of the many cylindrical color space models that are designed to accord with human perception of color with the three parameters. Lch has been adopted by information visualization practitioners to present data without the bias implicit in using varying saturation. They are, in general, designed to have characteristics of both cylindrical translations of the RGB color space, such as HSL and HSV, and the L*a*b* color space. Derivation Color-making attributes HCL concerns the following attributes of color appearance: ; Hue: The "attribute of a visual sensation according to which an area appears to be similar to one of the perceived colors: red, yellow, green, and blue, or to a combination of two of them".Fairchild (2005)/ref> ; Lightness, value: The "brightness relative to the brightness of a similarly illuminated white". ; Luminance (''Y'' or ''L''v,Ω): The radiance weighted by the effect of each wavelength on a typica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Munsell Color System
The Munsell color system is a color space that specifies colors based on three properties of color: hue (basic color), value (lightness), and colorfulness, chroma (color intensity). It was created by Albert Henry Munsell, Albert H. Munsell in the first decade of the 20th century and adopted by the United States Department of Agriculture (USDA) as the official color system for soil research in the 1930s. Several earlier color order systems in the field of colorimetry had placed colors into a three-dimensional color solid of one form or another, but Munsell was the first to separate hue, value, and chroma into Color difference#Tolerance, perceptually uniform and independent dimensions, and he was the first to illustrate the colors systematically in three-dimensional space. Munsell's system, particularly the later renotations, is based on rigorous measurements of human subjects' color vision, visual responses to color, putting it on a firm experimental scientific basis. Because of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tint, Shade And Tone
In color theory, a tint is a mixture of a color with white, which increases lightness, while a shade is a mixture with black, which increases darkness. A tone is produced either by mixing a color with gray, or by both tinting and shading. Mixing a color with any neutral color (black, gray, and white) reduces the chroma, or colorfulness, while the perceived hue can be affected slightly (see Abney effect and Bezold-Brücke shift). In the graphic arts, especially printmaking and drawing, "tone" has a different meaning, referring to areas of continuous color, produced by various means, as opposed to the linear marks made by an engraved or drawn line. In common language, the term ''shade'' can be generalized to encompass any varieties of a particular color, whether technically they are shades, tints, tones, or slightly different hues. Meanwhile, the term ''tint'' can be generalized to refer to any lighter or darker variation of a color (e.g. " tinted windows"). When mixi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls within a given solid angle. The procedure for conversion from spectral radiance to luminance is standardized by the CIE and ISO. Brightness is the term for the ''subjective'' impression of the ''objective'' luminance measurement standard (see for the importance of this contrast). The SI unit for luminance is candela per square metre (cd/m2). A non-SI term for the same unit is the nit. The unit in the Centimetre–gram–second system of units (CGS) (which predated the SI system) is the stilb, which is equal to one candela per square centimetre or 10 kcd/m2. Description Luminance is often used to characterize emission or reflection from flat, diffuse surfaces. Luminance levels indicate how much luminous power could be det ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stevens's Power Law
Stevens' power law is an empirical relationship in psychophysics between an increased intensity or strength in a physical stimulus and the perceived magnitude increase in the sensation created by the stimulus. It is often considered to supersede the Weber–Fechner law, which is based on a logarithmic relationship between stimulus and sensation, because the power law describes a wider range of sensory comparisons, down to zero intensity. The theory is named after psychophysicist Stanley Smith Stevens (1906–1973). Although the idea of a power law had been suggested by 19th-century researchers, Stevens is credited with reviving the law and publishing a body of psychophysical data to support it in 1957. The general form of the law is :\psi(I) = k I ^a, where ''I'' is the intensity or strength of the stimulus in physical units (energy, weight, pressure, mixture proportions, etc.), ψ(''I'') is the magnitude of the sensation evoked by the stimulus, ''a'' is an exponent that depen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CIECAM02
In colorimetry, CIECAM02 is the color appearance model published in 2002 by the International Commission on Illumination (CIE) Technical Committee 8-01 (''Color Appearance Modelling for Color Management Systems'') and the successor of Color appearance model#CIECAM97s, CIECAM97s. The two major parts of the model are its chromatic adaptation transform, CIECAT02, and its equations for calculating mathematical correlates for the six technically defined dimensions of color appearance: brightness (luminance), lightness, colorfulness, Colorfulness#Chroma, chroma, Colorfulness#Saturation, saturation, and hue. Brightness is the subjective appearance of how bright an object appears given its surroundings and how it is illuminated. Lightness is the subjective appearance of how light a color appears to be. Colorfulness is the degree of difference between a color and gray. Colorfulness#Chroma, Chroma is the colorfulness relative to the brightness of another color that appears white under sim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chroma (color)
The Munsell color system is a color space that specifies colors based on three properties of color: hue (basic color), value (lightness), and colorfulness, chroma (color intensity). It was created by Albert Henry Munsell, Albert H. Munsell in the first decade of the 20th century and adopted by the United States Department of Agriculture (USDA) as the official color system for soil research in the 1930s. Several earlier color order systems in the field of colorimetry had placed colors into a three-dimensional color solid of one form or another, but Munsell was the first to separate hue, value, and chroma into Color difference#Tolerance, perceptually uniform and independent dimensions, and he was the first to illustrate the colors systematically in three-dimensional space. Munsell's system, particularly the later renotations, is based on rigorous measurements of human subjects' color vision, visual responses to color, putting it on a firm experimental scientific basis. Because of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CIELUV
In colorimetry, the CIE 1976 ''L''*, ''u''*, ''v''* color space, commonly known by its abbreviation CIELUV, is a color space adopted by the International Commission on Illumination (CIE) in 1976, as a simple-to-compute transformation of the 1931 CIE XYZ color space, but which attempted perceptual uniformity. It is extensively used for applications such as computer graphics which deal with colored lights. Although additive mixtures of different colored lights will fall on a line in CIELUV's uniform chromaticity diagram (called the ''CIE 1976 UCS''), such additive mixtures will not, contrary to popular belief, fall along a line in the CIELUV color space unless the mixtures are constant in lightness. Historical background CIELUV is an Adams chromatic valence color space and is an update of the CIE 1964 (''U''*, ''V''*, ''W''*) color space (CIEUVW). The differences include a slightly modified lightness scale and a modified uniform chromaticity scale, in which one of the coordina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Munsell Color System
The Munsell color system is a color space that specifies colors based on three properties of color: hue (basic color), value (lightness), and colorfulness, chroma (color intensity). It was created by Albert Henry Munsell, Albert H. Munsell in the first decade of the 20th century and adopted by the United States Department of Agriculture (USDA) as the official color system for soil research in the 1930s. Several earlier color order systems in the field of colorimetry had placed colors into a three-dimensional color solid of one form or another, but Munsell was the first to separate hue, value, and chroma into Color difference#Tolerance, perceptually uniform and independent dimensions, and he was the first to illustrate the colors systematically in three-dimensional space. Munsell's system, particularly the later renotations, is based on rigorous measurements of human subjects' color vision, visual responses to color, putting it on a firm experimental scientific basis. Because of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CIE 1931 Color Space
In 1931, the International Commission on Illumination (CIE) published the CIE 1931 color spaces which define the relationship between the visible spectrum and human color vision. The CIE color spaces are mathematical models that comprise a "standard observer", which is a static idealization of the color vision of a normal human. A useful application of the CIEXYZ colorspace is that a mixture of two colors in some proportion lies on the straight line between those two colors. One disadvantage is that it is not perceptually uniform. This disadvantage is remedied in subsequent color models such as CIELUV and CIELAB, but these and modern color models still use the CIE 1931 color spaces as a foundation. The CIE (from the French name " Commission Internationale de l'éclairage" - International Commission on Illumination) developed and maintains many of the standards in use today relating to colorimetry. The CIE color spaces were created using data from a series of experiments, where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
