{{Short description|Device that converts images into electronic signals}}
An '''image sensor''' or '''imager''' s a device that detects and conveys information used to form an image. It does so by converting the variable [[attenuation]] of light [[wave]]s (as they [[refraction|pass through]] or [[reflection (physics)|reflect off]] objects) into [[signal (electrical engineering)|signals]], small bursts of [[electric current|current]] that convey the information. The waves can be light or other [[electromagnetic radiation]]. Image sensors are used in [[electronics|electronic]] imaging devices of both [[analogue electronics|analog]] and [[digital electronics|digital]] types, which include [[digital camera]]s, [[camera module]]s, [[camera phones]], [[optical mouse]] devices, [[medical imaging]] equipment, [[night vision]] equipment such as [[thermography|thermal imaging]] devices, [[radar]], [[sonar]], and others. As [[technological change|technology changes]], electronic and [[digital imaging]] tends to replace chemical and analog imaging.
The two main types of electronic image sensors are the [[charge-coupled device]] (CCD) and the [[active-pixel sensor]] ([[CMOS]] sensor). Both CCD and CMOS sensors are based on [[metal–oxide–semiconductor]] (MOS) technology, with CCDs based on [[MOS capacitor]]s and CMOS sensors based on [[MOSFET]] (MOS field-effect transistor) [[amplifiers]]. Analog sensors for invisible radiation tend to involve [[vacuum tube]]s of various kinds, while digital sensors include [[flat-panel detector]]s.
