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Scanning
- (in terms of TV) - Scanning
is the technique of building up a TV
image as a series of horizontal lines. The beams
from the electron guns (if electronic guns are used) at the rear of the
picture tube scan the image
from right to left and top to bottom. The number of lines is a measure
of the resolution. A standard
(analog) TV picture uses interlaced
scanning, where each complete picture is displayed as 2 frames; the
first frame having the odd-numbered lines and the second frame having
the
even-numbered lines. Each screen phosphor emits light for a short time
after being struck by the moving electron beam. This, together with
persistence of human vision, gives the appearance of a flicker-free
complete
continuous image.
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