Active pixel sensors (APS) are image sensors.

The image sensing circuitry may be implemented using charge-coupled devices, active pixel sensor circuits, or any other light sensing mechanism.

In applications where a somewhat lower quality can be tolerated, such as webcams, cheaper active pixel sensors (CMOS) are generally used.

In reference to digital cameras, APS may also mean active pixel sensor, a type of CMOS image sensor.

This is given, for an active pixel sensor, by the voltage at the input (gate) of the read transistor divided by the charge which generates that voltage, .

In response, Fossum invented the CMOS Active pixel sensor (APS) camera-on-a-chip technology.

A CMOS imaging chip is a type of active pixel sensor made using the CMOS semiconductor process.

The two main types of sensors are charge-coupled devices, in which the photocharge is shifted to a central charge-to-voltage converter, and CMOS or active pixel sensors.

Another type of active pixel sensor is the hybrid infrared focal plane array (IRFPA) designed to operate at cryogenic temperatures in the infrared spectrum.

Many other small image sensor companies also sprang to life shortly thereafter due to the accessibility of the CMOS process and all quickly adopted the active pixel sensor approach.

Early analog sensors were video camera tubes; most currently used are digital charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) active pixel sensors.

There are many types of active pixel sensors including the CMOS APS used most commonly in cell phone cameras, web cameras and in some DSLRs.

Further, the built-in iSight has a plastic lens, is fixed-focus, and uses a CMOS active pixel sensor, rather than the CCD used in the external iSight.

In 1990s,Bedabrata Pain along with his four friends invented the active pixel sensor technology that produced the world's smallest camera and has been inducted to the US Space Technology Hall of Fame.

IVS digital low-light and night vision products, based on Intevac's patented Electron Bombarded Active Pixel Sensor (EBAPS ) CMOS technology include:

The first patent of an Active Pixel Sensor (APS), submitted by JPL's Eric Fossum, led to the spin-off of Photobit, which was eventually bought by Micron Technology.

Three-CCD cameras are often referred to as "three-chip" cameras; this term is actually more descriptive and inclusive, since it includes cameras that use CMOS active pixel sensors instead of CCDs.

Several manufacturers have developed video laryngoscopes which employ digital technology such as the complementary metal-oxide semiconductor active pixel sensor (CMOS APS) to generate a view of the glottis so that the trachea may be intubated.

In the summer of 1998, Viaspace also signed a memorandum of understanding with Omicron Technologies to form a joint venture for the commercialization of applications of a technology known as Active Pixel Sensors (APS).

The CMOS active pixel sensor "camera-on-a-chip" developed by Dr. Eric Fossum and his team in the early 1990s achieved the first step of realizing the modern camera phone as described in a March 1995 Business Week article.

Because the MOS process was so variable and MOS transistors had characteristics that changed over time (Vth instability), the CCD's charge-domain operation was more manufacturable and quickly eclipsed MOS passive and active pixel sensors.

The term active pixel sensor was coined by Tsutomu Nakamura who worked on the Charge Modulation Device active pixel sensor at Olympus, and more broadly defined by Eric Fossum in a 1993 paper.

This active pixel sensor equips, for example, the Xperia pro, an Android smartphone from Sony Ericsson, which was launched in October 2011, and the Exmor R sensor allows the camera of the smartphone to capture high definition movies and stills in low lit areas.

The term active pixel sensor is also used to refer to the individual pixel sensor itself, as opposed to the image sensor; in that case the image sensor is sometimes called an active pixel sensor imager, active-pixel image sensor, or active-pixel-sensor (APS) imager.