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Brightness
 
 
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Brightness is an attribute of visual perception
Visual perception

Visual perception is the ability to interpret information from visible light reaching the eye. The resulting perception is also known as eyesight, sight or vision....
 in which a source appears to be radiating or reflecting light
Light

Light, or visible light, is electromagnetic radiation of a wavelength that is Visible spectrum to the human eye , or up to 380?750 nm. In the broader field of physics, light is sometimes used to refer to electromagnetic radiation of all wavelengths, whether visible or not....
. In other words, brightness is the perception elicited by the luminance
Luminance

Luminance is a Photometry measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle....
 of a visual target. This is a subjective
Subjective

Subjective may refer to:* Subjectivity, a subject's perspective, particularly feelings, beliefs, and desires*Subjective experience, the sensory buzz and awareness associated with a conscious mind...
 attribute
Attribute

The word "attribute" can refer to:* In philosophy, property , an abstraction of a characteristic of an entity or substance* In art, an object that identifies a figure, most commonly referring to objects held by saints - see emblem...
/property
Property

Property is any physical or virtual entity that is ownership by an individual or jointly by a group of individuals. An owner of property has the right to consumption, sell, Renting, mortgage, transfer and exchange his or her property....
 of an object being observed.

efined by the US Federal Glossary of Telecommunication Terms (FS-1037C
Federal Standard 1037C

Federal Standard 1037C, entitled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended....
), "brightness" should now be used only for non-quantitative references to physiological sensations and perceptions of light.

A given target luminance can elicit different perceptions of brightness in different contexts; see, for example, White's illusion
White's illusion

White's illusion is an optical illusion illustrating the fact that the same target luminance can elicit different perceptions of brightness in different contexts....
 and Wertheimer
Wertheimer

Wertheimer is an Ashkenazi Jews Jewish surname:People with this surname include:* Alain Wertheimer & Gerard Wertheimer, French Jewish billionaires owners of Chanel...
-Benary illusion.

In the RGB color space
RGB color space

An RGB color space is any additive color space based on the RGB color model. A particular RGB color space is defined by the three chromaticity of the red, green, and blue additive primaries, and can produce any chromaticity that is the triangle defined by those primary colors....
, brightness can be thought of as the arithmetic mean
Arithmetic mean

In mathematics and statistics, the arithmetic mean of a list of numbers is the sum of all of the list divided by the number of items in the list....
 μ of the red, green, and blue color coordinates (although some of the three components make the light seem brighter than others, which, again, may be compensated by some display systems automatically):

Brightness is also a color coordinate in the HSB or HSV color space (hue, saturation
Saturation (color theory)

In colorimetry and color theory, colorfulness, chroma, and saturation are related but distinct concepts referring to the perceived intensity of a specific color....
, and brightness or value).

With regard to star
Star

A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
s, brightness is quantified as apparent magnitude
Apparent magnitude

The apparent magnitude of a celestial body is a measurement of its brightness as seen by an observer on Earth, normalized to the value it would have in the absence of the Earth's atmosphere....
 and absolute magnitude
Absolute magnitude

In astronomy, absolute magnitude measures a celestial object's intrinsic brightness. To derive the absolute magnitude from the observed apparent magnitude of a celestial object its value is corrected for distance to the observer....
.

term "brightness" is also used in discussions of sound timbre
Timbre

In music, timbre is the quality of a musical note or sound or tone that distinguishes different types of sound production, such as voices or musical instruments....
s, in a rough analogy with visual brightness.






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Encyclopedia


Brightness is an attribute of visual perception
Visual perception

Visual perception is the ability to interpret information from visible light reaching the eye. The resulting perception is also known as eyesight, sight or vision....
 in which a source appears to be radiating or reflecting light
Light

Light, or visible light, is electromagnetic radiation of a wavelength that is Visible spectrum to the human eye , or up to 380?750 nm. In the broader field of physics, light is sometimes used to refer to electromagnetic radiation of all wavelengths, whether visible or not....
. In other words, brightness is the perception elicited by the luminance
Luminance

Luminance is a Photometry measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle....
 of a visual target. This is a subjective
Subjective

Subjective may refer to:* Subjectivity, a subject's perspective, particularly feelings, beliefs, and desires*Subjective experience, the sensory buzz and awareness associated with a conscious mind...
 attribute
Attribute

The word "attribute" can refer to:* In philosophy, property , an abstraction of a characteristic of an entity or substance* In art, an object that identifies a figure, most commonly referring to objects held by saints - see emblem...
/property
Property

Property is any physical or virtual entity that is ownership by an individual or jointly by a group of individuals. An owner of property has the right to consumption, sell, Renting, mortgage, transfer and exchange his or her property....
 of an object being observed.

Terminology


"Brightness" was formerly used as a synonym for the photometric
Photometry (optics)

Photometry is the science of measurement of light, in terms of its perceived brightness to the human eye. It is distinct from radiometry, which is the science of measurement of radiant energy in terms of absolute power; rather, in photometry, the radiant power at each wavelength is weighted by a luminosity function that models human b...
 term luminance
Luminance

Luminance is a Photometry measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle....
 and (incorrectly) for the radiometric term radiance
Radiance

Radiance and spectral radiance are radiometry measures that describe the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle in a specified direction....
. As defined by the US Federal Glossary of Telecommunication Terms (FS-1037C
Federal Standard 1037C

Federal Standard 1037C, entitled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended....
), "brightness" should now be used only for non-quantitative references to physiological sensations and perceptions of light.

A given target luminance can elicit different perceptions of brightness in different contexts; see, for example, White's illusion
White's illusion

White's illusion is an optical illusion illustrating the fact that the same target luminance can elicit different perceptions of brightness in different contexts....
 and Wertheimer
Wertheimer

Wertheimer is an Ashkenazi Jews Jewish surname:People with this surname include:* Alain Wertheimer & Gerard Wertheimer, French Jewish billionaires owners of Chanel...
-Benary illusion.

In the RGB color space
RGB color space

An RGB color space is any additive color space based on the RGB color model. A particular RGB color space is defined by the three chromaticity of the red, green, and blue additive primaries, and can produce any chromaticity that is the triangle defined by those primary colors....
, brightness can be thought of as the arithmetic mean
Arithmetic mean

In mathematics and statistics, the arithmetic mean of a list of numbers is the sum of all of the list divided by the number of items in the list....
 μ of the red, green, and blue color coordinates (although some of the three components make the light seem brighter than others, which, again, may be compensated by some display systems automatically):

Brightness is also a color coordinate in the HSB or HSV color space (hue, saturation
Saturation (color theory)

In colorimetry and color theory, colorfulness, chroma, and saturation are related but distinct concepts referring to the perceived intensity of a specific color....
, and brightness or value).

With regard to star
Star

A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
s, brightness is quantified as apparent magnitude
Apparent magnitude

The apparent magnitude of a celestial body is a measurement of its brightness as seen by an observer on Earth, normalized to the value it would have in the absence of the Earth's atmosphere....
 and absolute magnitude
Absolute magnitude

In astronomy, absolute magnitude measures a celestial object's intrinsic brightness. To derive the absolute magnitude from the observed apparent magnitude of a celestial object its value is corrected for distance to the observer....
.

Brightness of sounds

The term "brightness" is also used in discussions of sound timbre
Timbre

In music, timbre is the quality of a musical note or sound or tone that distinguishes different types of sound production, such as voices or musical instruments....
s, in a rough analogy with visual brightness. Timbre researchers consider brightness to be one of the perceptually strongest distinctions between sounds, and formalize it acoustically as an indication of the amount of high-frequency content in a sound, using a measure such as the spectral centroid
Spectral centroid

The spectral centroid is a measure used in digital signal processing to characterise an audio spectrum. It indicates where the "center of mass" of the spectrum is....
.

See also


  • Luma (video)
    Luma (video)

    As applied to video signals, luma represents the brightness in an image . Luma is typically paired with Chrominance. Luma represents the achromatic image without any color, while the chroma components represent the color information....
  • Luminance (relative)


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