Charge-Coupled device

[sajiv]

A charge-coupled device (CCD) is a light-sensitive integrated circuit that stores and displays the data for an image in such a way that each pixel (picture element) in the image is converted into an electical charge the intensity of which is related to a color in the color spectrum. For a system supporting 65,535 colors, there will be a separate value for each color that can be stored and recovered. CCDs are now commonly included in digital still and video cameras. They are also used in astronomical telescopes, scanners, and bar code readers. The devices have also found use in machine vision for robots, in optical character recognition (OCR), in the processing of satellite photographs, and in the enhancement of radar images, especially in meteorology.

A CCD in a digital camera improves resolution compared with older technologies.� Some digital cameras produce images having more than one million pixels, yet sell for under $1,000. The term megapixel has been coined in reference to such cameras. Sometimes a camera with an image of 1,024 by 768 pixels is given the label "megapixel," even though it technically falls short of the mark. Another asset of the CCD is its high degree of sensitivity.� A good CCD can produce an image in extremely dim light, and its resolution does not deteriorate when the illumination intensity is low, as is the case with conventional cameras.

The CCD was invented in 1969 at Bell Labs, now part of Lucent Technologies, by George Smith and Willard Boyle.