CCD image sensors (charge coupled device) are electronic devices that are capable of transforming a light pattern (image) into an electric charge pattern (an electronic image). The CCD consists of several individual elements that have the capability of collecting, storing and transporting electrical charge from one element to another. This together with the photosensitive properties of silicon, is used to design image sensors. Each photosensitive element will then represent a picture element (pixel). With semiconductor technologies and design rules, structures are made that form lines, or matrices of pixels. One or more output amplifiers at the edge of the chip collect the signals from the CCD. An electronic image can be obtained by - after having exposed the sensor with a light pattern - applying series of pulses that transfer the charge of one pixel after another to the output amplifier, line after line. The output amplifier converts the charge into a voltage. External electronics will transform this output signal into a form suitable for monitors or frame grabbers. CCDs have extremely low noise figures.