How Camera Sensors Work: From Light to Image Data

Automatically transcribed from the original recording. Small transcription errors may remain.

Have you ever wondered how camera sensors work? Once light travels through the lens and hits the sensor in the back of the camera, it is essentially turning photons into electrons on a grid where each unit on this grid represents the brightness or color of a pixel. The sensor is composed of a device that converts light into an electrical current called a photodiode. When a photon hits the diode, it creates voltage. Now the voltage is quite minimal at first, and this is where an amplifier is used to increase the voltage. The amplifier knows precisely how much voltage is needed to determine a pixel's brightness thanks to a comparator. Comparators work off of bits, and the higher the bit count, the more precise the image. Color comes in from something called a Bayer filter. While a comparator determines the intensity of brightness, the Bayer filter determines the intensity of a particular color. Each pixel or each section of our grid is composed of two greens and a blue. They have two greens because our eyes are more sensitive to green compared to blue and red. We also use green to determine luminance or brightness values as well. Finally, the process of creating an image from a sensor using a bare filter is called demosaicing. This is done by the camera's image processor going pixel by pixel, line by line on the grid, until you have a complete image.