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= images =
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Introduction
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An image or picture is a visual representation. An image can be
two-dimensional, such as a drawing, painting, or photograph, or
three-dimensional, such as a carving or sculpture. Images may be
displayed through other media, including a projection on a surface,
activation of electronic signals, or digital displays; they can also
be reproduced through mechanical means, such as photography,
printmaking, or photocopying. Images can also be animated through
digital or physical processes.
In the context of signal processing, an image is a distributed
amplitude of color(s). In optics, the term 'image' (or 'optical
image') refers specifically to the reproduction of an object formed by
light waves coming from the object.
A 'volatile image' exists or is perceived only for a short period.
This may be a reflection of an object by a mirror, a projection of a
camera obscura, or a scene displayed on a cathode-ray tube. A 'fixed
image', also called a hard copy, is one that has been recorded on a
material object, such as paper or textile.
A mental image exists in an individual's mind as something one
remembers or imagines. The subject of an image does not need to be
real; it may be an abstract concept such as a graph or function or an
imaginary entity. For a mental image to be understood outside of an
individual's mind, however, there must be a way of conveying that
mental image through words or visual productions of the subject.
Two-dimensional images
========================
The broader sense of the word 'image' also encompasses any
two-dimensional figure, such as a map, graph, pie chart, painting, or
banner. In this wider sense, images can also be rendered manually,
such as by drawing, the art of painting, or the graphic arts (such as
lithography or etching). Additionally, images can be rendered
automatically through printing, computer graphics technology, or a
combination of both methods.
A two-dimensional image does not need to use the entire visual system
to be a visual representation. An example of this is a grayscale
("black and white") image, which uses the visual system's sensitivity
to brightness across all wavelengths without taking into account
different colors. A black-and-white visual representation of something
is still an image, even though it does not fully use the visual
system's capabilities.
On the other hand, some processes can be used to create visual
representations of objects that are otherwise inaccessible to the
human visual system. These include microscopy for the magnification of
minute objects, telescopes that can observe objects at great
distances, X-rays that can visually represent the interior structures
of the human body (among other objects), magnetic resonance imaging
(MRI), positron emission tomography (PET scans), and others. Such
processes often rely on detecting electromagnetic radiation that
occurs beyond the light spectrum visible to the human eye and
converting such signals into recognizable images.
Three-dimensional images
==========================
Aside from sculpture and other physical activities that can create
three-dimensional images from solid material, some modern techniques,
such as holography, can create three-dimensional images that are
reproducible but intangible to human touch. Some photographic
processes can now render the illusion of depth in an otherwise "flat"
image, but "3-D photography" (stereoscopy) or "3-D film" are optical
illusions that require special devices such as eyeglasses to create
the illusion of depth.
Moving images
===============
"Moving" two-dimensional images are actually illusions of movement
perceived when still images are displayed in sequence, each image
lasting less, and sometimes much less, than a fraction of a second.
The traditional standard for the display of individual frames by a
motion picture projector has been 24 frames per second (FPS) since at
least the commercial introduction of "talking pictures" in the late
1920s, which necessitated a standard for synchronizing images and
sounds. Even in electronic formats such as television and digital
image displays, the apparent "motion" is actually the result of many
individual lines giving the impression of continuous movement.
This phenomenon has often been described as "persistence of vision": a
physiological effect of light impressions remaining on the retina of
the eye for very brief periods. Even though the term is still
sometimes used in popular discussions of movies, it is not a
scientifically valid explanation. Other terms emphasize the complex
cognitive operations of the brain and the human visual system.
"Flicker fusion", the "phi phenomenon", and "beta movement" are among
the terms that have replaced "persistence of vision", though no one
term seems adequate to describe the process.
Cultural and other uses
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Image-making seems to have been common to virtually all human cultures
since at least the Paleolithic era. Prehistoric examples of rock
art--including cave paintings, petroglyphs, rock reliefs, and
geoglyphs--have been found on every inhabited continent. Many of these
images seem to have served various purposes: as a form of
record-keeping; as an element of spiritual, religious, or magical
practice; or even as a form of communication. Early writing systems,
including hieroglyphics, ideographic writing, and even the Roman
alphabet, owe their origins in some respects to pictorial
representations.
Meaning and signification
===========================
Images of any type may convey different meanings and sensations for
individual viewers, regardless of whether the image's creator intended
them. An image may be taken simply as a more or less "accurate" copy
of a person, place, thing, or event. It may represent an abstract
concept, such as the political power of a ruler or ruling class, a
practical or moral lesson, an object for spiritual or religious
veneration, or an object--human or otherwise--to be desired. It may
also be regarded for its purely aesthetic qualities, rarity, or
monetary value. Such reactions can depend on the viewer's context. A
religious image in a church may be regarded differently than the same
image mounted in a museum. Some might view it simply as an object to
be bought or sold. Viewers' reactions will also be guided or shaped by
their education, class, race, and other contexts.
The study of emotional sensations and their relationship to any given
image falls into the categories of aesthetics and the philosophy of
art. While such studies inevitably deal with issues of meaning,
another approach to signification was suggested by the American
philosopher, logician, and semiotician Charles Sanders Peirce.
"Images" are one type of the broad category of "signs" proposed by
Peirce. Although his ideas are complex and have changed over time, the
three categories of signs that he distinguished stand out:
# The "icon," which relates to an object by resemblance to some
quality of the object. A painted or photographed portrait is an icon
by virtue of its resemblance to the painting's or photograph's
subject. A more abstract representation, such as a map or diagram, can
also be an icon.
# The "index," which relates to an object by some real connection. For
example, smoke may be an index of fire, or the temperature recorded on
a thermometer may be an index of a patient's illness or health.
# The "symbol," which lacks direct resemblance or connection to an
object but whose association is arbitrarily assigned by the creator or
dictated by cultural and historical habit, convention, etc. The color
red, for example, may connote rage, beauty, prosperity, political
affiliation, or other meanings within a given culture or context; the
Swedish film director Ingmar Bergman claimed that his use of the color
in his 1972 film 'Cries and Whispers' came from his personal
visualization of the human soul.
A single image may exist in all three categories at the same time. The
Statue of Liberty provides an example. While there have been countless
two-dimensional and three-dimensional "reproductions" of the statue
(i.e., "icons" themselves), the statue itself exists as
* an "icon" by virtue of its resemblance to a human woman (or, more
specifically, previous representations of the Roman goddess Libertas
or the female model used by the artist Frederic-Auguste Bartholdi).
* an "index" representing New York City or the United States of
America in general due to its placement in New York Harbor, or with
"immigration" from its proximity to the immigration center at Ellis
Island.
* a "symbol" as a visualization of the abstract concept of "liberty"
or "freedom" or even "opportunity" or "diversity".
Critiques of imagery
======================
The nature of images, whether three-dimensional or two-dimensional,
created for a specific purpose or only for aesthetic pleasure, has
continued to provoke questions and even condemnation at different
times and places. In his dialogue, 'The Republic', the Greek
philosopher Plato described our apparent reality as a copy of a higher
order of universal forms. As copies of a higher reality, the things we
perceive in the world, tangible or abstract, are inevitably imperfect.
Book 7 of 'The Republic' offers Plato's "Allegory of the Cave," where
ordinary human life is compared to being a prisoner in a darkened cave
who believes that shadows projected onto the cave's wall comprise
actual reality. Since art is itself an imitation, it is a copy of that
copy and all the more imperfect. Artistic images, then, not only
misdirect human reason away from understanding the higher forms of
true reality, but in imitating the bad behaviors of humans in
depictions of the gods, they can corrupt individuals and society.
Echoes of such criticism have persisted across time, accelerating as
image-making technologies have developed and expanded immensely since
the invention of the daguerreotype and other photographic processes in
the mid-19th century. By the late 20th century, works like John
Berger's 'Ways of Seeing' and Susan Sontag's 'On Photography'
questioned the hidden assumptions of power, race, sex, and class
encoded in even realistic images, and how those assumptions and such
images may implicate the viewer in the voyeuristic position of a
(usually) male viewer. The documentary film scholar Bill Nichols has
also studied how apparently "objective" photographs and films still
encode assumptions about their subjects.
Images perpetuated in public education, media, and popular culture
have a profound impact on the formation of such mental images:
Religious critiques
=====================
Despite, or perhaps because of, the widespread use of religious and
spiritual imagery worldwide, the making of images and the depiction of
gods or religious subjects has been subject to criticism, censorship,
and criminal penalties. The Abrahamic religions (Judaism,
Christianity, and Islam) all have had admonitions against the making
of images, even though the extent of that proscription has varied with
time, place, and sect or denomination of a given religion. In Judaism,
one of the Ten Commandments given by God to Moses on Mount Sinai
forbids the making of "any graven image, or any likeness [of any
thing] that [is] in heaven above, or that [is] in the earth beneath,
or that [is] in the water under earth." In Christian history, periods
of iconoclasm (the destruction of images, especially those with
religious meanings or connotations) have broken out from time to time,
and some sects and denominations have rejected or severely limited the
use of religious imagery. Islam tends to discourage religious
depictions, sometimes quite rigorously, and often extends that to
other forms of realistic imagery, favoring calligraphy or geometric
designs instead. Depending on time and place, photographs and
broadcast images in Islamic societies may be less subject to outright
prohibition. In any religion, restrictions on image-making are
especially targeted to avoid depictions of "false gods" in the form of
idols. In recent years, militant extremist groups such as the Taliban
and ISIS have destroyed centuries-old artifacts, especially those
associated with other religions.
In culture
============
Virtually all cultures have produced images and applied different
meanings or applications to them. The loss of knowledge about the
context and connection of an image to its object is likely to result
in different perceptions and interpretations of the image and even of
the original object itself.
Through human history, one dominant form of imagery has been in
relation to religion and spirituality. Such images, whether in the
form of idols that are objects of worship or that represent some other
spiritual state or quality, have a different status as artifacts when
copies of such images sever links to the spiritual or supernatural.
The German philosopher and essayist Walter Benjamin brought particular
attention to this point in his 1935 essay "The Work of Art in the Age
of Mechanical Reproduction."
Benjamin argues that the mechanical reproduction of images, which had
accelerated through photographic processes in the previous one hundred
years or so, inevitably degrades the "authenticity" or quasi-religious
"aura" of the original object. One example is Leonardo da Vinci's
'Mona Lisa', originally painted as a portrait, but much later, with
its display as an art object, it developed a "cult" value as an
example of artistic beauty. Following years of various reproductions
of the painting, the portrait's "cult" status has little to do with
its original subject or the artistry. It has become famous for being
famous, while at the same time, its recognizability has made it a
subject to be copied, manipulated, satirized, or otherwise altered in
forms ranging from Marcel Duchamp's 'L.H.O.O.Q'. to Andy Warhol's
multiple silk-screened reproductions of the image.
In modern times, the development of "non-fungible tokens" (NFTs) has
been touted as an attempt to create "authentic" or "unique" images
that have a monetary value, existing only in digital format. This
assumption has been widely debated.
Other considerations
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The development of synthetic acoustic technologies and the creation of
sound art have led to considering the possibilities of a sound-image
made up of irreducible phonic substance beyond linguistic or
musicological analysis.
Still or moving
=================
A ' is a single static image. This phrase is used in photography,
visual media, and the computer industry to emphasize that one is not
talking about movies, or in very precise or pedantic technical writing
such as a standard.
A ' is typically a movie (film) or video, including digital video. It
could also be an animated display, such as a zoetrope.
A still frame is a still image derived from one frame of a moving one.
In contrast, a film still is a photograph taken on the set of a movie
or television program during production, used for promotional
purposes.
In image processing, a picture function is a mathematical
representation of a two-dimensional image as a function of two spatial
variables. The function f(x,y) describes the intensity of the point at
coordinates (x,y).
Literature
============
In literature, a "mental image" may be developed through words and
phrases to which the senses respond. It involves picturing an image
mentally, also called imagining, hence imagery. It can both be
figurative and literal.
See also
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* Cinematography
* Computer-generated imagery
* Digital image
* Drawing
* Fine-art photography
* Graphics
* Image editing
* Imaging
* Painting
* Photograph
* Pictorial script
* Satellite image
* Visual arts
License
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Original Article: http://en.wikipedia.org/wiki/images
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