Image sensors in video cameras are of two types:
- CCD (Charged Coupled Device).
- CMOS (Complementary Metal Oxide Semiconductor)
What’s the difference between CCD and CMOS?
If you’re new to the image sensor game, it’s important to understand how an image sensor works before learning the difference between CCD and CMOS.
- Light enters a video camera through the lens and hits the image sensor.
- The sensor converts it to an electrical signal which is then sent to an image processor.
This process happens both with CCD and CMOS
CCD vs CMOS Image Sensor Image Quality
CCD : Separate Image Processing Function
The difference is in a CCD chip, the sensor sends the signal to a separate image processor.
As such, image processing in a CCD chip requires a longer time and more power consumption.
This is not a drawback actually. The result is clearer, high-quality, less grainy images with minimum video noise.
CMOS : Integrated Image Processing Function
In a CMOS image sensor, no separate image processing is required. When light is converted into an electrical signal, the signal is processed within the image sensor itself.
There is no need for the sensor to send the signal to a separate image processor.
In other words, conversion is a single-step process involving each pixel.
So, CMOS uses up less power (you’ll have a longer battery life) and cost lower than CCD but they don’t deliver the image quality one may come to expect.
The general conclusion is CCD image sensors exhibit a greater sensitivity to light and have the advantage of producing clearer images in low-light conditions.
Therefore, they are popularly used in video cameras and CCTV cameras.
If you’re buying a CCTV camera, all things considered, go for a CCD surveillance camera if you have the choice.
Advancement in CMOS Technology
That said, CMOS is fast catching up with the image quality offered by CCD.
CCD now seems not to be able to catch up with developments in the CMOS world.
Modern products like mobile phones, DSLR cameras, and cinematography cameras rely on CMOS technology.
Even CCTVs are beginning to utilize CMOS technology.
Sony, a major manufacturer of CCD sensors has announced that it will most likely discontinue CCD sensors by 2025.
Still, experts are agreed that a CCD image sensor performs better when it comes to capturing fast-moving objects.
The Focal Digital Imaging A–Z By Adrian Davies, Focal Press