Monday, November 2, 2009

Raster scanning process

the purpose of a video camera is to convert an image infront of camera into an electrical signal.
an electrical signal has only one value(either on or off)at any instant of time and is one dimensional, but the image is two dimensional having many values at all the different positions in the image.
conversion of 2-dimensional(2D) image to 1-dimensional electrical signal is accomplished by scanning that image in an orderly pattern called a Raster.
with scanning, we move a sensing point rapidly over the image fast enough to capture the complete image, before it moves too much.
as the sensing point moves the electrical output changes in response to brightness or colour of the image beneath the sensing point.
the varying electrical signal from the senser represents the image as the series of values spread out in time. this is called a video signal.
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