Interlaced Scanning

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interlaced scanning

[¦in·tər¦lāst ′skan·iŋ]
A scanning process in which the distance from center to center of successively scanned lines is two or more times the nominal line width, so that adjacent lines belong to different fields. Also known as line interlace.

Interlaced Scanning


a method of television scanning in which the transmitted image on the target of the television camera tube and the television frame on the screen of the picture tube are produced by a single scanning of two frame fields; the odd lines are scanned and reproduced for the first field, and the even lines, which are positioned in the spaces between the lines of the first field, make up the second field. When scanning of the second field has been completed, the beam is returned to the point where the scanning of the first field begins.

Interlaced scanning is used in television systems with an odd number of scanning lines z because only in this case is there a nonintegral number of lines z/2 in each field, so that the beginning of scannings of the first and second fields (and, as a result, the television rasters of these fields) are displaced along the vertical by half the displacement of adjacent lines in a field. It permits a 2:1 reduction in the frame frequency needed for line scanning (since the flicker frequency of the images on the screen is equal to the field frequency) and thereby reduces by half the upper frequency limit of the television signal spectrum.


See references under TELEVISION.


References in periodicals archive ?
Third, the number of lines traced on a TV screen can vary from 480 to 1080 and use either interlaced scanning or the single-step progressive scanning technique employed by computer manufacturers.
Interlaced scanning is a system that was devised in the early days of television to reduce the flicker generated in a progressive scanning system without using a wider bandwidth.
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Progressive scanning delivers a picture in 480p resolution, which is clearer than the 480i image provided by interlaced scanning (all DVD players now on the U.
1): 1080i -- An HD standard based on interlaced scanning using 1080 effective scanning lines (*2): 720p -- An HD standard based on progressive scanning using 720 effective scanning lines About Panasonic