A system and method for averaging incident light on plural pixels using a CMOS sensor is provided. The process includes resetting all pixels in a given region during a reset phase; and reading a voltage of a floating reset node as a function of time during a measurement phase. During the reset phase, an access select signal and a reset voltage are both high. The measurement phase begins when the access select signal is low and the reset voltage is still high. The system and method may be used to perform automatic exposure control and automatic white balancing operations.