in optics, likeness or counterpart of an object produced when rays of light coming from that object are reflected from a mirror
or are refracted by a lens
. An image of an object is also formed when this light passes through a very small opening like that of a pinhole camera (which has no lens). Images are classed as real or virtual. A real image occurs when the rays of light from the object actually converge to form an image and can be seen on a screen placed at the point of convergence. For example, the image produced by the refraction of light rays by a convex lens (when the distance between the object and the lens is greater than the focal length of the lens) is real, and it appears on the side of the lens opposite the one on which the object is present. On the other hand, a virtual image occurs when the prolongations of the light rays converge to form an image, but the light rays themselves do not reach the point of convergence. Thus a virtual image cannot be seen on a screen. The image in a plane mirror is virtual. It appears to be behind the mirror, at a distance equal to that of the object in front, although the rays of light from the object do not penetrate the mirror but are reflected from it. Images of the same size as the object are sometimes produced, as in the case of the plane mirror, but in other cases they are larger, and in still others, smaller. They are sometimes erect and in other cases are inverted. The size of the image and whether it is erect or inverted, real or virtual, depend on the distance of the object from the lens or mirror relative to the focal length and on the type of lens or mirror (plane, convex, or concave) employed.
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image The representation of an object formed from the light or other electromagnetic radiation reflected or transmitted by the object and collected and brought to a focus by a telescope, camera, or similar instrument. Depending on the type of object being observed and telescope involved, images may be viewed directly by the observer, photographed, or recoded or analyzed by other instruments or electronic equipment. In an optical telescope, light is gathered by the primary mirror or objective, which bends the incoming rays until they meet at the focal point where the image is generated. In astronomy, the objects observed are so distant that images formed by all telescopes are upside down and real – that is, the light that produces them actually passes through them, making it possible for them to be projected onto a screen, for example. Such images are magnified by lenses in the eyepiece. In a refractor or Schmidt–Cassegrain, an angled device called a star diagonal, containing a prism or mirror, can be inserted in front of the eyepiece. Apart from making the telescope easier to use by making the eyepiece more accessible, this item of equipment turns the image up the right way but laterally inverts it, swapping it left to right as in a mirror. Radio telescopes work in a similar way to optical instruments, producing images from radio waves and converting them to a visible form by computer processing. See also imaging
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
Any representation of form or features, especially one of the entire figure of a person; a statue, effigy, bust, relief, or intaglio. See also: Design
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
in philosophy, the result and ideal form of the reflection of an object in human consciousness, arising from practical sociohistorical experience, on the basis and in the form of a system of signs. On the sensory level of knowledge, images consist of sensations, perceptions, and representations. On the level of logical thought, they consist of concepts, judgments, and conclusions.
The objective sources of images are objects and phenomena in the material world. In this sense, an image is secondary in relation to its original. The material substratum of an image consists of the corresponding neurophysiological processes occurring in the human or animal cortex. The material embodiment of an image takes the form of practical acts, language, and various semiotic models. The artistic image is a specific form of image.
The uniqueness of an image lies in its subjective and ideal quality: it has no independent existence outside of its relationship to its material substratum—the brain and the object reflected in the brain. An image is objective in content to the degree to which it faithfully reflects an object. But the image of an object never exhausts the full wealth of its characteristics and relationships: the original is richer than its copy. Once it arises, the image acquires a relatively independent character and plays an active role in human and animal behavior, regulating behavior and actions.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
One of two groups of side bands generated in the process of modulation; the unused group is referred to as the unwanted image.
The scene reproduced by a television or facsimile receiver.
A copy of the information contained in one medium recorded on a different data medium.
The input reflection coefficient corresponding to the reflection coefficient of a specified load when the load is placed on one side of a waveguide junction and a slotted line is placed on the other.
For a point x in the domain of a function ƒ, the point ƒ(x).
For a subset A of the domain of a function ƒ, the set of all points that are equal to ƒ(x) for some point x in A.
An optical counterpart of a self-luminous or illuminated object formed by the light rays that traverse an optical system; each point of the object has a corresponding point in the image from which rays diverge or appear to diverge.
Any reproduction of an object produced by means of focusing light, sound, electron radiation, or other emanations coming from the object or reflected by the object.
A representation of a sensory experience, occurring in the brain.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
Any representation of form or features, but esp. one of the entire figure of a person; a statue, effigy, bust, relief, intaglio, etc.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
1. an optically formed reproduction of an object, such as one formed by a lens or mirror
2. the pattern of light that is focused on to the retina of the eye
3. Psychol the mental experience of something that is not immediately present to the senses, often involving memory
4. a mental picture or association of ideas evoked in a literary work, esp in poetry
5. a figure of speech, such as a simile or metaphor
a. (of a point) the value of a function, f(x), corresponding to the point x
b. the range of a function
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
1. <data, graphics> Data representing a two-dimensional scene.
A digital image is composed of pixels arranged in a
rectangular array with a certain height and width. Each pixel
may consist of one or more bits of information, representing
the brightness of the image at that point and possibly
including colour information encoded as RGB
Images are usually taken from the real world via a digital camera
, frame grabber
, or scanner
; or they may be
generated by computer, e.g. by ray tracing
See also image formats
, image processing
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)
image(1) (noun) A picture; graphic; photo. See graphics.
(2) (verb) To capture a scene (see imaging).
(3) A RAM or storage snapshot (see system image).
|The First Commercial Photographic Method|
|Daguerreotype film was a highly polished silver surface on a copper plate exposed to iodine fumes to make it light sensitive. Invented by Louis Jacques Daguerre, from the 1840s to the 1850s, daguerroeotype images were a favorite of the rich and famous.|
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