simulacrum definition of simulacrum in the Free Online Encyclopedia.

image, in optics, likeness or counterpart of an object produced when rays of light coming from that object are reflected from a mirror mirror, in optics, a reflecting surface that forms an image of an object when light rays coming from that object fall upon it (see reflection ). Usually mirrors are made of plate glass, one side of which is coated with metal or some special preparation to serve as a
..... Click the link for more information. or are refracted by a lens lens, device for forming an image of an object by the refraction of light. In its simplest form it is a disk of transparent substance, commonly glass, with its two surfaces curved or with one surface plane and the other curved.
..... Click the link for more information. . 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.

(1) A picture. A graphic. See graphics.

(2) To picture. To display.

(3) See system image.

image - 1. 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 triples.

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 software.

See also image formats, image processing.

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