CCD versus CMOS Today
We have shared our measurement data of the latest CCD and CMOS industrial image sensors. This includes sensitivity, low light performance, and MTF. These results show dramatic improvements in image quality of CMOS image sensors and explain the transition to more and more CMOS cameras even for demanding, high-performance applications.
The figure below presents the sensitivity (QE/Dark Noise) for two sensors at two temperatures: room temperature, and a higher temperature. The curves show that the CMOS sensor (Sony IMX174) is more sensitive than the CCD sensor (Sony ICX674) at all wavelengths. Also, you can see that the sensors perform worse at higher temperatures than at room temperature, as expected.
To demonstrate the comparison of low light performance, we shared stills from real time video at Full HD and 60 frames per second of a CCD camera and a CMOS camera (utilizing the same image sensors mentioned before). The light level of 0.3 Lux is just an example; it doesn’t show the limiting light levels of these image sensors. Both images are color-processed; lower light levels can be achieved with monochrome image sensors. We wanted to compare real life situations so the cameras are uncooled and running at full speed around room temperature. The scene is simply a “hard to photograph” package materials to show off what can be done.
Current Status High Definition CCD vs. CMOS
CCD – 0.3 Lux
CMOS – 0.3Lux
We also created a video comparing video of both cameras side-by side at the 2015 SPIE DSS:
MTF provides an indication of the sharpness of the image or image quality and is determined by both the lens AND the sensor. The new SONY CMOS image sensor IMX174 is using deep trench isolation (DTI) in a device with larger pixels and benefits from an excellent MTF in the NIR range. In fact, this CMOS sensor even outperforms the ICX674 CCD from Sony, which has been the golden reference for sensor performance. In the chart below, we show the MTF of both sensors at various wavelengths.
CCD versus CMOS in the future
So with all of these improvements and changeover to more CMOS cameras, how do we expect things to continue? Our observations are that the noise levels will continue to decrease with CMOS global shutter image sensors for even better low light performance.
Sony isn’t the only image sensor developer. Other companies have to challenge to match or surpass the performance as we measured today, or they will find their own niche in which specialty sensors will have added value. We eagerly look forward to what is out there in CMOS image sensors.
These are our observations. Leave us a comment on what you see for the future.