The inventors of the charge-coupled device (CCD), Willard Boyle and George E. Smith, could not have imagined in their wildest dreams that one day their invention would make film obsolete and ruin Kodak. Yet, shortly after they were invented in 1969, it became obvious, that CCDs were photosensitive. A year later, CCDs – which were originally devised as a means of data storage – were used to construct the very first photo sensor. From the mid-seventies successors of this sensor had begun to take over television cameras. In 1976 one of the lead physicists at Kodak, Bryce Bayer, had developed the Bayer filter, and in doing so had ultimately enabled Kodak’s downfall. From then on, CCD sensors were used in almost every digital camera, up until 6 or 7 years ago, at which point they were driven from the market by CMOS sensors. Thanks to their faster readout and lower noise at higher sensitivities, CMOS sensors were providing the advantages and features photographers and film makers had dreamed about for the longest time: mind-blowingly high ISOs and 1080p and 4k video. 😉
The two videos, which I have embedded down below, illustrate the functioning of CCD and CMOS sensors. The former capture and record an entire image at a time (so called “Global Shutter”). The brightness values are then sequentially copied from one line to the next, until they are read one final time and passed on to the image processor.
CMOS sensors capture an image line by line and pass on the brightness values to the image processor immediately. The faster readout of the sensor makes higher frame rates possible, but also causes the rolling shutter effect.