Image sensor

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An image sensor is a device that converts a visual image to an electric signal. It is used chiefly in digital cameras and other imaging devices. It is usually an array of charge-coupled devices (CCD) or CMOS sensors such as active pixel sensors.

There are several main types of color image sensors, differing by the means of the color separation mechanism:

Bayer sensor, low-cost and most common, using a Bayer filter that passes red, green, or blue light to selected pixels, forming interlaced grids sensitive to red, green, and blue. The image is then interpolated using a demosaicing algorithm.

Foveon X3 sensor, using an array of layered sensors where every pixel contains three stacked sensors sensitive to the individual colors.

3CCD, using three discrete image sensors, with the color separation done by a dichroic prism. Considered the best quality, and generally more expensive than single-CCD sensors.

[edit] Specialty sensors

Special sensors are used for various applications. The most important are the sensors for thermal imaging, creation of multi-spectral images, gamma cameras, sensor arrays for x-rays, and highly sensitive arrays for astronomy.