Image sensor with black level control and low power consumption

An image sensor comprising a pixel array (10), comprising at least one row of pixels, each pixel having a light receiving element and a reset switch (41-45) connected to a reset node of said light receiving element, divided into an effective pixel region (102) and an optical black pixel region (10); and a read-out circuit, for scanning said pixel array (10) to read out signals from said pixels, including a black clamp circuit for holding a signal from said optical black pixel region (101) as an integrated dark current signal and for correcting a signal from said effective pixel region (102) with said integrated dark current signal, wherein said optical black pixel region comprises a potential averaging line (30) commonly connected to said reset nodes of a plurality of pixels in a pixel row.