CCD vs CMOS

Every digital camera (or other digital imaging device) has the image sensor. What is image sensor? The job of an image sensor is converts light into electric charge, and process it into electronic signals. So, we can preview the picture which is captured by digital camera on our computer, in digital format.

There have two main image sensors: Charge-Coupled Device (CCD), and Complementary Metal-Oxide-Semiconductor (CMOS).

CCD 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 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.

Traditionally, here is some noticeable differences between CCD and CMOS.

- CCD create high quality and low noise images. CMOS are more susceptible to noise.
- CCD consume lots of power. CMOS consume little power.
- CCD will be more expensive than CMOS
- CCD device is less complex than CMOS

Today there is no clear advantage in image quality for both CCD and CMOS. Because CMOS designers have devoted intense effort to archieving high image quality, while CCD designers have lowered their power requirements and pixel sizes. As a result, you can find CCDs in low-cost low-power cellphone cameras and CMOS sensors in high-performance professional (such as digital SLR camera) and industrial cameras, directly contradicting the early stereotypes.

Refer here for more feature comparison between CCD and CMOS.

Article Reference:
1. http://en.wikipedia.org/wiki/Image_sensor
2. http://www.dalsa.com/corp/markets/CCD_vs_CMOS.aspx
3. http://electronics.howstuffworks.com/question362.htm