Saturation (oversaturation) is the largest possible signal that a CCD sensor can record. The signal is measured as a function of the amount of charge that is generated in each pixel of the CCD sensor. Each potential well, which represents a CCD sensor pixel, has a maximum capacity that depends on the size of the pixel - small pixels (6x6 µm) can hold about 50,000 electrons, medium pixels (10x10 µm) can hold 100,000 electrons and large pixels (25x25 µm) can hold up to 300,000 electrons.
