A character, or a combination of bits, that is not valid in a given system according to specified criteria, such as with respect to a specified alphabet, a particular pattern of bits, a rule of formation, or a check code. [From Weik '89] Synonyms false character, forbidden character, improper character, unallowable character, unused character.

Abbreviation for instrument landing system.

1. Itensity modulation,
2. Element Management Layer,
3. Instant Messaging,
4. IP Multimedia,
5. Intermodulation.

IM-Home Serving System

In the field of image processing, a two-dimensional representation of a scene. Synonym picture.

A hypothetical mirror-image, i.e., virtual-image, of an antenna, i.e., antenna element, considered to extend as far below ground, i.e., the ground plane, as the actual antenna is above the ground plane.
Note 1: The image antenna is helpful in calculating electric field vectors, magnetic field vectors, and electromagnetic fields emanating from the real antenna, particularly in the vicinity of the… (Read More →)

The transducing of the information in a real image into the photographic or electronic medium.
Note: Normally in motion-reproducing systems, synchronous audio information is simultaneously transduced. [After SMPTE]

1. Application of an appropriate transfer function to an image signal so as to limit dynamic range.
2. Application of bandwidth limiting or bit-rate reduction to an image signal in order to bring it within the limitations of a lower capacity channel. [After SMPTE]

In video technology, a technique used to improve contrast and picture clarity by flattening the camera response to 400 lines (by aperture correction) and applying an additional correction to increase the depth of modulation in the range of 250 to 300 lines (in an NTSC system), both vertically and horizontally.
Note: Image enhancement produces a correction signal with symmetrical overshoots… (Read More →)

The formalization of a multidisciplinary agreement—regarding digital image characteristics, such as the structure of digital image files, the organization of the image data itself, and the definition of fully flexible, interoperable, scalable, and extensible systems—which agreement facilitates the exchange of such files across various technology interfaces.