CMOS v/s CCD
CMOS and CCD are the basic technologies behind digital photographic image capture. This article explains the meaning of the terms and compares the two technologies.
CMOS stands for Complementary Metal Oxide Semiconductor and is the most commonly-used type of design for semi-conductors. The CMOS image sensor adapts CMOS architecture for image capture and was originally developed by NASA in the mid-90's. It is relatively inexpensive to manufacture thanks to an architecture that can be easily produced by standard chip-fabrication processes.
| CCD stands for Charged Couple Device, a technology that pre-dates CMOS and was originally devised for general computer memory. CCD was adapted for TV cameras in the 1970's and subsequently for video cameras and many other devices in the 1980's. CCD is technically superior to CMOS although CMOS sensors are continually improving. CCDs are manufactured by a specialised process and are therefore rather more expensive to fabricate than are CMOS sensors. |  |
Both CCD and CMOS work by converting differences between points of light on the capture surface into an electrical charges, and thence into binary data. However while CCD transports the image data across the chip to a dedicated processor, CMOS sensors rely on transistors embedded throughout the chip surface.
CCD has been developed over several decades as a specialised digital video solution, and accordingly:
- offers superior light sensitivity
- is better in low light situations
- offers better colours and sharper images
- offers superior production homogeniety with less manufacturing deviation between units
- reduces background noise providing greater image clarity