1. An image sensor comprising a pixel array, each pixel of said pixel array comprising: a photodetector formed in a semiconductor substrate and having a charge collection region for receiving photocharge representative of incident light; a sink device formed in said semiconductor substrate and adjacent to said charge collection region having a gate overlying and insulated from said semiconductor substrate and receiving a responsivity control signal; and a readout circuit for transferring said photocharge collected by said charge collection region of said photodetector to an output in response to a select signal.