Image Sensor is a device that converts an optical image into an electronic signal. It is used mostly in digital cameras and other imaging devices. Modern image sensors are either CCD image sensors or CMOS image sensors. Today, most digital still cameras use either a CCD image sensor or a CMOS sensor. Both types of sensor accomplish the same task of capturing light and converting it into electrical signals. There are many parameters that can be used to evaluate the performance of an image sensor, including its dynamic range, its signal-to-noise ratio, its low-light sensitivity, etc.

Types of Image Sensors

  • Charge-Coupled Device (CCD) Image Sensor for still photography & videography
  • Complementary Metal–Oxide–Semiconductor (CMOS) Image Sensor for still photography & videography
  • Bayer Sensor (Bayer Filter Mask) for color serparation and filtering over the CCD image sensor
  • Three-CCD (3CCD) Image Sensor is for color separation and filtering
  • Electron-Multiplying CCD (EMCCD) Image Sensor is a CMOS image sensor with better sogna-to-noise ratio efficiency.
  • Intensified Charge-Coupled Device (ICCD) Image Sensor is a CCD that is optically connected to an image intensifier that is mounted in front of the CCD.
  • Frame Transfer CCD Image Sensor is a specialized CCD, often used in astronomy and some professional video cameras, designed for high exposure efficiency and correctness.
  • X3 Image Sensor is a type of CMOS image sensor used for color separation and filtering via the inherent wavelength-dependent absorption property
  • Super CCD Image Sensor is a higher resiolution charge-coupled device that has been developed by Fujifilm.
  • Hole Accumulation Diode (HAD) is a patented technique of the Sony Corporation to reduce electronic noise in a CCD or CMOS imaging sensor by reducing the so-called “dark” current that occur in the absence of light falling on the imager for noise reduction and enhanced image quality.

CCD vs CMOS Image Sensors Comparison

  • CCD image sensor is an analog device. When light strikes the chip it is held as a small electrical charge in each photo sensor. The charges are converted to voltage one pixel at a time as they are read from the chip. Additional circuitry in the camera converts the voltage into digital information.
  • CMOS imaging chip is a type of active pixel sensor made using the CMOS semiconductor process. Extra circuitry next to each photo sensor converts the light energy to a voltage. Additional circuitry on the chip may be included to convert the voltage to digital data.
  • Neither technology has a clear advantage in image quality. On one hand, CCD sensors are more susceptible to vertical smear from bright light sources when the sensor is overloaded; high-end frame transfer CCDs in turn do not suffer from this problem. On the other hand, CMOS sensors are susceptible to undesired effects that come as a result of rolling shutter.
  • CMOS can potentially be implemented with fewer components, use less power, and/or provide faster readout than CCDs. CCD is a more mature technology and is in most respects the equal of CMOS. CMOS sensors are less expensive to manufacture than CCD sensors.