When browsing the different cameras available from Dun-Bri, you will notice video camera manufacturers that offer two types of image sensors: CCD and CMOS. These image sensors are used to produce the digital images during recording. Both types are made of silicon and use similar mechanisms to process images, but each type uses different technology to capture and transfer image signals, and some users find that there can be a significant difference between the end results.
In essence, a CCD video camera and a CMOS video camera have different processing efficiencies, different qualities, different paired accessories, and are even different prices. Understanding how each type of sensor works and the strengths and weaknesses of each helps buyers determine the technology that is suitable for their video camera needs.
CCD (Charged Coupled Device)
The CCD video camera has been the go-to sensor since its development. In a CCD video camera, light hitting the image sensor is converted to an electrical signal. This electron packet must then be transferred one pixel at a time through an output node to an image processor, at which point it is converted to voltage. The voltage is then buffered and sent out from the chip as an analogue signal.
The CCD process involves an extra step over CMOS sensors (the transfer of each pixel to an image processor) and therefore requires more time and energy to process imagery. However, because each pixel is devoted to capturing light, CCD sensors have a high output uniformity that results in cleaner, higher-quality images. In a three-CCD (3CCD) camera, the imaging system uses three separate CCDs, with each one measuring a different primary colour (red, green, or blue). This allows them to provide an even better image quality while also producing lower noise.
CCD sensors are also distinct from CMOS for their use of global shutters instead of rolling shutters. Global shutters process an entire image at once by exposing the full frame for a predetermined amount of time. This means the entire sensor gathers an equal amount of light at once. Global shutters are free of the image distortion related to rapid movement or flashes of light.
CMOS (Complementary Metal Oxide Semiconductor)
Unlike CCD sensors, CMOS sensors have circuitry at the pixel level. This means that every pixel on the sensor is read and transmitted simultaneously, preparing voltage for the chip. The chip then uses additional technology, such as amplifiers, noise correction, and digitisation, to convert the voltage to digital data. This means that CMOS sensors do not require a separate image processor. Because CMOS sensors are able to convert visual information to digital data more quickly than CCDs, they require less power, which preserves battery life. However, the extra technology on the sensor crowds the pixels, limiting their ability to capture light and resulting in generally poorer visual clarity in the final image.
CMOS sensors are commonly designed with rolling shutters, especially on commercial applications. This means that the image frame is exposed from one side to the other, instead of all at once as on CCD sensors. For example, a reversing camera using a CMOS sensor may record data in a “rolling” sweep from left to right, or top to bottom. This results in the potential for a few types of distortion not found on CCD sensors.
So, which one is best for me?
CCD technology was traditionally the dominant sensor since the development of the two forms in the late 1960s and early 1970s. This was mostly due to CCD’s ability to produce better image quality than CMOS with the manufacturing abilities of the time. However, developments in lithography in the 1990s allowed designers to produce CMOS sensors in a way that provided quality images at a lower cost than CCD. It was these developments that led to the inclusion of CMOS sensors in digital cameras, ultimately making the products affordable for the general public.
Although CCDs have set the benchmarks for image sensor performance, developments in CMOS have greatly reduced the differences in image quality between them. Meanwhile, developers of CCD sensors have worked to lower the cost of the technology. Contradictory to past perceptions of the sensors, modern forms of CCDs have become inexpensive enough to be used in applications like cell phone cameras, while some high-performance cameras in professional and industrial applications use CMOS technology.
In general, CCD cameras can produce higher resolution images with less noise. They are also more sensitive to light, which means that they produce higher-quality images in low-light settings. CMOS cameras are more energy efficient, which means the battery life is longer. They are also generally less expensive. However, many of these differences have already become negligible in modern products. For example, a high-end CMOS camera may produce clearer images than a mid-range CCD camera.
Ultimately, buyers of commercial video camera products may find that the sensor technology used in a video camera is less relevant than the manufacturer and the other tech specs of the camera. Modern developments in each type of sensor technology have made them quite comparable in terms of the amount of power used, their price, and their image quality. Some companies have taken the best part of both technologies and found a way to meld them together to make a great video camera.
For more help in choosing, please get in touch.