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The visible spectrum is the portion of the
electromagnetic spectrum The electromagnetic spectrum is the range of frequency, frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energy, photon energies. The electromagnetic spectrum covers electromagnetic waves with f ...

electromagnetic spectrum
that is
visible Visibility is in meteorology, a measure of the distance at which an object or light can be seen. Visibility may also refer to: * Visual perception ** Naked-eye visibility * A measure of turbidity in water quality control * Interferometric visibili ...
to the
human eye The human eye is a sense organ A sense is a biological system A biological system is a complex biological network, network which connects several biologically relevant entities. Biological organization spans several scales and are determined ...

human eye
.
Electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space and time, and the related entities of energy and force. ...

Electromagnetic radiation
in this range of
wavelength In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular su ...

wavelength
s is called ''
visible light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that is visual perception, perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nano ...
'' or simply
light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that is visual perception, perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nan ...

light
. A typical
human eye The human eye is a sense organ A sense is a biological system A biological system is a complex biological network, network which connects several biologically relevant entities. Biological organization spans several scales and are determined ...

human eye
will respond to wavelengths from about 380 to about 750
nanometers one nanometric Scanning_Tunneling_Microscope.html"_;"title="carbon_nano_tube,_photographed_with_Scanning_Tunneling_Microscope">carbon_nano_tube,_photographed_with_Scanning_Tunneling_Microscope_ file:EM_Spectrum_Properties_edit.svg.html" ;"title= ...
. In terms of frequency, this corresponds to a band in the vicinity of 400–790  terahertz. These boundaries are not sharply defined and may vary per individual. Under optimal conditions these limits of human perception can extend to 310 nm (
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, ...

ultraviolet
) and 1100 nm (
near infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natur ...
). The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well. The spectrum does not contain all the
color Color (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American Engli ...

color
s that the human
visual system The visual system comprises the sensory organ A sense is a biological system A biological system is a complex network which connects several biologically relevant entities. Biological organization spans several scales and are determined b ...
can distinguish. '' Unsaturated colors'' such as
pink Pink is the color of a namesake flower that is a pale tint of red. It was first used as a color name in the late 17th century. According to surveys in Europe and the United States, pink is the color most often associated with charm, politeness, ...

pink
, or
purple Purple is any of a variety of color Color (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the ...

purple
variations like
magenta Magenta () is a color that is variously defined as purplish-red, reddish-purple Purple is any of a variety of color Color (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States Eng ...

magenta
, for example, are absent because they can only be made from a mix of multiple wavelengths. Colors containing only one wavelength are also called ''pure colors'' or spectral colors. Visible wavelengths pass largely unattenuated through the
Earth's atmosphere The atmosphere of Earth is the layer of gas Gas is one of the four fundamental states of matter (the others being solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The mo ...

Earth's atmosphere
via the "
optical window The optical window is a range of wavelengths that are not blocked by the Earth, earth's atmosphere. The window runs from around 300 nanometers (Ultraviolet, ultraviolet-B) up into the range the human eye can detect, roughly 400–700 nm and continu ...
" region of the electromagnetic spectrum. An example of this phenomenon is when clean air
scatters
scatters
blue light more than red light, and so the midday sky appears blue (apart from the area around the sun which appears white because the light is not scattered as much). The optical window is also referred to as the "visible window" because it overlaps the human visible response spectrum. The
near infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natur ...
(NIR) window lies just out of the human vision, as well as the medium wavelength infrared (MWIR) window, and the long-wavelength or far-infrared (LWIR or FIR) window, although other animals may experience them.


History

In the 13th century,
Roger Bacon Roger Bacon (; la, Rogerus or ', also '' Rogerus''; ), also known by the scholastic accolade It was customary in the European Middle Ages, more precisely in the period of scholasticism which extended into early modern times, to designate th ...
theorized that
rainbow A rainbow is a meteorological Meteorology is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on weather forecasting Weather forecasting is the application of sc ...

rainbow
s were produced by a similar process to the passage of light through glass or crystal. In the 17th century,
Isaac Newton Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician A mathematician is someone who uses an extensive knowledge of mathematics Mathematics (from Greek: ) includes the study of such topics a ...

Isaac Newton
discovered that prisms could disassemble and reassemble white light, and described the phenomenon in his book ''
Opticks ''Opticks: or, A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light'' is a book by English natural philosopher Isaac Newton Sir Isaac Newton (25 December 1642 – 20 March Old Style and New Style dates, 1726/ ...

Opticks
''. He was the first to use the word ''spectrum'' (
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, it became ...

Latin
for "appearance" or "apparition") in this sense in print in 1671 in describing his
experiment An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into Causality, cause-and-effect by demonstrating what outcome oc ...

experiment
s in
optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...

optics
. Newton observed that, when a narrow beam of
sunlight Sunlight is a portion of the given off by the , in particular , , and light. On , sunlight is and through , and is obvious as when the Sun is above the . When direct is not blocked by s, it is experienced as sunshine, a combination of b ...

sunlight
strikes the face of a glass
prism A prism An optical prism is a transparent optics, optical element with flat, polished surfaces that refraction, refract light. At least one surface must be angled—elements with two parallel surfaces are not prisms. The traditional geometrical ...

prism
at an angle, some is reflected and some of the beam passes into and through the glass, emerging as different-colored bands. Newton hypothesized light to be made up of "corpuscles" (particles) of different colors, with the different colors of light moving at different speeds in transparent matter, red light moving more quickly than violet in glass. The result is that red light is bent (
refracted In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior throu ...

refracted
) less sharply than violet as it passes through the prism, creating a spectrum of colors. Newton originally divided the spectrum into six named colors:
red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength Image:dominant wavelength.png, frame, Dominant/complementary wavelength example on the CIE color ...

red
,
orange Orange most often refers to: *Orange (colour), occurs between red and yellow in the visible spectrum *Orange (fruit), the fruit of the tree species '' Citrus'' × ''sinensis'' ** Orange blossom, its fragrant flower *Some other citrus or citrus-li ...
,
yellow Yellow is the color between green and Orange (colour), orange on the Visible spectrum, spectrum of visible light. It is evoked by light with a dominant wavelength of roughly 575585 Nanometre, nm. It is a primary color in subtractive color syst ...

yellow
,
green Green is the color between blue and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 Nanometre, nm. In subtractive color systems, used in painting and color printing, it is created by ...

green
,
blue Blue is one of the three primary colours of pigments in painting and traditional colour theory In the visual arts The visual arts are art forms such as painting Painting is the practice of applying paint Paint is any pig ...

blue
, and
violet Violet may refer to: Common meanings * Violet (color), a spectral color with wavelengths shorter than blue * One of a list of plants known as violet, particularly: ** Viola (plant), ''Viola'' (plant), a genus of flowering plants Places United ...
. He later added
indigo InterGlobe Aviation Ltd d/b/a IndiGo is an Indian low-cost airline headquartered in Gurgaon, Haryana, India. It is the largest List of airlines of India, airline in India by passengers carried and fleet size, with a 57% domestic market shar ...

indigo
as the seventh color since he believed that seven was a perfect number as derived from the
ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek (, ), refers collectively to the diale ...
sophists A sophist ( el, σοφιστής, ''sophistes'') was a teacher in ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a civilization belonging to a period of History of Greece, Greek history from the Greek Dark Ages of the 12th–9 ...
, of there being a connection between the colors, the musical notes, the known objects in the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

Solar System
, and the days of the week. The human eye is relatively insensitive to indigo's frequencies, and some people who have otherwise-good vision cannot distinguish indigo from blue and violet. For this reason, some later commentators, including
Isaac Asimov Isaac Asimov (; 1920 – April 6, 1992) was an American writer and professor of biochemistry at Boston University. During his lifetime, Asimov was considered one of the "Big Three" science fiction writers, along with Robert A. Heinlein and A ...
, have suggested that indigo should not be regarded as a color in its own right but merely as a shade of blue or violet. Evidence indicates that what Newton meant by "indigo" and "blue" does not correspond to the modern meanings of those color words. Comparing Newton's observation of prismatic colors to a color image of the visible light spectrum shows that "indigo" corresponds to what is today called blue, whereas his "blue" corresponds to
cyan Cyan () is the color between green Green is the between and on the . It is evoked by light which has a of roughly 495570 . In systems, used in painting and color printing, it is created by a combination of yellow and ; in the , u ...

cyan
. In the 18th century,
Johann Wolfgang von Goethe Johann Wolfgang von Goethe (28 August 1749 – 22 March 1832) was a German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of G ...

Johann Wolfgang von Goethe
wrote about optical spectra in his ''
Theory of Colours ''Theory of Colours'' (German: ''Zur Farbenlehre'') is a book by Johann Wolfgang von Goethe about the poet's views on the nature of color, colours and how these are perceived by humans. It was published in German in 1810 and in English in 1840. ...
''. Goethe used the word ''spectrum'' (''Spektrum'') to designate a ghostly optical
afterimage An afterimage is an image that continues to appear in the eyes after a period of exposure to the original image. An afterimage may be a normal phenomenon (physiological afterimage) or may be pathological ( palinopsia). Illusory palinopsia may be ...

afterimage
, as did
Schopenhauer Arthur Schopenhauer (; ; 22 February 1788 – 21 September 1860) was a German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citize ...
in ''
On Vision and Colors ''On Vision and Colors'' (originally translated as ''On Vision and Colours''; german: Ueber das Sehn und die Farben) is a treatise by Arthur Schopenhauer Arthur Schopenhauer (; ; 22 February 1788 – 21 September 1860) was a Germans, German ...
''. Goethe argued that the continuous spectrum was a compound phenomenon. Where Newton narrowed the beam of light to isolate the phenomenon, Goethe observed that a wider aperture produces not a spectrum but rather reddish-yellow and blue-cyan edges with
white White is the lightest color Color (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the Unite ...

white
between them. The spectrum appears only when these edges are close enough to overlap. In the early 19th century, the concept of the visible spectrum became more definite, as light outside the visible range was discovered and characterized by
William Herschel Sir Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a spe ...

William Herschel
(
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior ...

infrared
) and
Johann Wilhelm Ritter Johann Wilhelm Ritter (16 December 1776 – 23 January 1810) was a German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of Germany ...

Johann Wilhelm Ritter
(
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, ...

ultraviolet
),
Thomas Young
Thomas Young
,
Thomas Johann Seebeck Thomas Johann Seebeck (; 9 April 1770 – 10 December 1831) was a Baltic German physicist, who, in 1822, observed a relationship between heat and magnetism. Later, in 1823, Ørsted called this phenomenon thermoelectric effect. Seebeck was bor ...

Thomas Johann Seebeck
, and others. Young was the first to measure the wavelengths of different colors of light, in 1802. The connection between the visible spectrum and
color vision Color vision, a feature of visual perception Visual perception is the ability to interpret the surrounding environment (biophysical), environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and ...

color vision
was explored by Thomas Young and
Hermann von Helmholtz Hermann Ludwig Ferdinand von Helmholtz (31 August 1821 – 8 September 1894) was a German physicist A physicist is a scientist A scientist is a person who conducts Scientific method, scientific research to advance knowledge in an Branch ...

Hermann von Helmholtz
in the early 19th century. Their theory of color vision correctly proposed that the eye uses three distinct receptors to perceive color.


Color perception across species

Many species can see light within frequencies outside the human "visible spectrum".
Bee Bees are flying insects closely related to wasps and ants, known for their role in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

Bee
s and many other insects can detect ultraviolet light, which helps them find
nectar Nectar is a sugar Sugar is the generic name for , soluble s, many of which are used in food. Simple sugars, also called s, include , , and . Compound sugars, also called s or double sugars, are molecules made of two monosaccharides jo ...
in flowers. Plant species that depend on insect pollination may owe reproductive success to their appearance in ultraviolet light rather than how colorful they appear to humans. Birds, too, can see into the ultraviolet (300–400 nm), and some have sex-dependent markings on their plumage that are visible only in the ultraviolet range. Many animals that can see into the ultraviolet range cannot see red light or any other reddish wavelengths. Bees' visible spectrum ends at about 590 nm, just before the orange wavelengths start. Birds can see some red wavelengths, although not as far into the light spectrum as humans.Varela, F. J.; Palacios, A. G.; Goldsmith T. M. (1993
"Color vision of birds"
pp. 77–94 in ''Vision, Brain, and Behavior in Birds'', eds. Zeigler, Harris Philip and Bischof, Hans-Joachim. MIT Press.
The popular belief that the common goldfish is the only animal that can see both infrared and ultraviolet light is incorrect, because goldfish cannot see infrared light. Most mammals are dichromatic, and dogs and horses are often thought to be color blind. They have been shown to be sensitive to colors, though not as many as humans. Some snakes can "see" radiant heat at
wavelength In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular su ...

wavelength
s between 5 and 30  μm to a degree of accuracy such that a blind
rattlesnake Rattlesnakes are a group of venomous snakes of the genus, genera ''Crotalus'' and ''Sistrurus'' of the subfamily Crotalinae (the pit vipers). All rattlesnakes are vipers. The scientific name ''Crotalus'' is derived from the Greek language, Greek ...

rattlesnake
can target vulnerable body parts of the prey at which it strikes, and other snakes with the organ may detect warm bodies from a meter away. It may also be used in
thermoregulation Thermoregulation is the ability of an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxo ...
and
predator Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical en ...

predator
detection.Greene HW. (1992). "The ecological and behavioral context for pitviper evolution", in Campbell JA, Brodie ED Jr. ''Biology of the Pitvipers''. Texas: Selva. . (See
Infrared sensing in snakes The ability to sense infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understoo ...
)


Spectral colors

Colors that can be produced by visible light of a narrow band of wavelengths (
monochromatic light A spectral color is a color Color ( American English), or colour ( Commonwealth English), is the characteristic of visual perception described through color ''categories'', with names such as red, orange (colour), orange, yellow, gree ...
) are called pure spectral colors. The various color ranges indicated in the illustration are an approximation: The spectrum is continuous, with no clear boundaries between one color and the next.


Color display spectrum

Color displays (e.g.
computer monitor A computer monitor is an output device that displays information in pictorial or text form. A monitor usually comprises a electronic visual display, visual display, electronic circuit, some circuitry, a casing, and a power supply. The display de ...

computer monitor
s and
television Television, sometimes shortened to TV or telly, is a telecommunication Telecommunication is the transmission of information by various types of technologies over wire A wire is a single usually cylindrical A cylinder (from Gre ...

television
s) cannot reproduce
''all'' colors discernible by a human eye
''all'' colors discernible by a human eye
. Colors outside the color
gamut In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain ''complete subset'' of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circu ...
of the device, such as most
spectral color A spectral color is a color that is evoked in a typical human by a single wavelength of light in the visible spectrum, or by a relatively narrow band of wavelengths, also known as Monochromatic radiation, monochromatic light. Every wavelength ...
s, can only be approximated. For color-accurate reproduction, a spectrum can be projected onto a uniform
gray Grey or gray (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American En ...
field. The resulting
mixed colors
mixed colors
can have all their
R, G, B coordinates
R, G, B coordinates
non-negative, and so can be reproduced without distortion. This accurately simulates looking at a spectrum on a gray background.


Spectroscopy

Spectroscopy Spectroscopy is the study of the interaction Interaction is a kind of action that occurs as two or more objects have an effect upon one another. The idea of a two-way effect is essential in the concept of interaction, as opposed to a one-way ...

Spectroscopy
is the study of objects based on the spectrum of color they emit, absorb or reflect. Visible-light spectroscopy is an important tool in
astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses mathematics, phys ...
(as is
spectroscopy Spectroscopy is the study of the interaction Interaction is a kind of action that occurs as two or more objects have an effect upon one another. The idea of a two-way effect is essential in the concept of interaction, as opposed to a one-way ...
at other wavelengths), where scientists use it to analyze the properties of distant objects.
Chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo du ...
s and small
molecule A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In physics, motion is the phenomenon ...

molecule
s can be detected in astronomical objects by observing
emission line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission (electromagnetic radiation), emission or absorption (electromagnetic radiation), absorption of light in a narrow frequency range, c ...
s and
absorption line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spect ...
s. For example,
Helium Helium (from el, ἥλιος, helios Helios; Homeric Greek: ), Latinized as Helius; Hyperion and Phaethon are also the names of his father and son respectively. often given the epithets Hyperion ("the one above") and Phaethon ("the shining" ...

Helium
was first detected by analysis of the spectrum of the
sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its own gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many othe ...

sun
. The shift in frequency of spectral lines is used to measure the
Doppler shift The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer (physics), observer who is moving relative to the wave source. It is named after the Austrian physicist ...

Doppler shift
(
redshift In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular ...

redshift
or
blueshift A blueshift is any decrease in wavelength (increase in energy), with a corresponding increase in frequency, of an electromagnetic wave Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of ph ...

blueshift
) of distant objects to determine their velocities towards or away from the observer.
Astronomical spectroscopy Astronomical spectroscopy is the study of astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and c ...
uses high-dispersion
diffraction grating In optics, a diffraction grating is an optical component with a periodic structure that diffraction, diffracts light into several beams travelling in different directions (i.e., different diffraction angles). The emerging coloration is a form ...

diffraction grating
s to observe spectra at very high spectral resolutions.


Properties


Heat

Although non-visible infrared light is more commonly thought of as "heat radiation", any frequency of light, including visible light, will heat surfaces that absorb them. A powerful source of purely visible light, such as a visible light laser, can char paper.


Biological effects

High-energy visible light (HEV light) (violet/blue light, with a wavelength of 400-450 nm) has a number of biological effects, especially on the eye. Studies by Harvard Health Publishing and France's
ANSES The National Social Security Administration ( es, Administración Nacional de la Seguridad Social; mostly known for its acronym ANSES) is a decentralized Argentine Government social insurance Social insurance is a concept where the governmen ...
found that exposure to blue light has a negative effect on sleep and can lead to impaired vision.


See also

*
High-energy visible light High-energy visible light (HEV light) is high-frequency, high-energy In , energy is the that must be to a or to perform on the body, or to it. Energy is a ; the law of states that energy can be in form, but not created or destroye ...
* Electromagnetic absorption by water#Visible region, why water is blue


References

{{Color topics
Color Artistic techniques Graphic design Image processing Visual perception Qualia Vision {{CatAutoTOC ...
Electromagnetic spectrum Vision