In common usage, an image (from Latin imago) or picture is an artifact that reproduces the likeness of some subject—usually a physical object or a person.

Images may be two dimensional (e.g. a photograph) or three dimensional (e.g. a statue). They are typically produced by optical devices—such as a cameras, mirrors, lenses, telescopes, microscopes, etc. and natural objects and phenomena, such as the human eye or water surfaces.

The word image is also used in the broader sense of any two-dimensional figure or illustration, e.g. a map, a graph, a pie chart, an abstract painting, etc. In this wider sense, images can also be produced manually (by drawing, painting, carving, etc.), by computer graphics technology, or a combination of the two (see pseudo-photograph).

A volatile image is one that exists only for a short period of time, e.g. the reflection of an object by a mirror, a projection of the sun on a wall by a pinhole camera, or a scene displayed on a cathode ray tube. A fixed image, also called hardcopy, is one that has been recorded on a material object, such as paper or textile.

A mental image exists in someone's mind: something one remembers or imagines. The subject of an image need not be real; it may be an abstract concept, such as a graph or function—or an imaginary entity or being.

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Specialised meanings

The word also has many specialized meanings in various disciplines and contexts:

In geometric optics, a lens can produce a real image or a virtual image.
In many other scientific and technical contexts, image usually means a two-dimensional signal—a physical phenomenon that can be modeled as a function from a two-dimensional domain (such as the plane or a rectangle) to some set of values, usually real numbers or vectors. This sense covers not only digital images but also analog ones, such as photographs. See image processing.
In computer graphics and digital image processing, the word image almost always means digital image or, by extension, any computer description of an image, e.g. a raster map, an image file, or a 2D computer graphics model. For embedding an image in a webpage, see HTML element#Images. A number of standard test images are in use in the image processing literature which serve as a common test of various image processing algorithms.
In computer science the word image can also mean an exact (bit-by-bit) copy of the contents of some device, such as a hard disk, floppy disk, CD-ROM, semiconductor storage chip, etc. In particular,
- A core image (or core dump, from magnetic core memory, the predominant RAM technology of the 1960s) is a faithful copy of the data stored in the main memory of a computer or process.
- An executable image is a structured file containing machine instructions and data, which can be loaded into a process's virtual memory and executed. See kernel (computers).
- A ROM image is a copy of the contents of an entire ROM chip, typically a video game executable, which may then be stored on another medium (in the case of copyrighted games, this comes under the category of software piracy).
In mathematics, an image of a function consist of the output values of the mathematical function.
In finance, the image is a coefficient (stock image) that bridges a stock's fundamental value and its market price.
In philosophy, an image is a conception or idea.
In religion, an image is an idol or icon, although these terms have very specialised meanings within certain sects and should not be held as always synonymous.
In social psychology an image is a representation.
In marketing image is often used as shorthand for the perception that consumers have for a brand, its values and its benefits (often referred to as brand image).
Image Comics is an American publisher of comic books.
The IMAGE spacecraft currently observing the Earth's magnetosphere

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External links

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