An image sensor comprises an array of pixels comprising: a pinned photodiode; a first sense node A; a second sense node B; a transfer gate TX connected between the pinned photodiode and the first sense node A; a first reset transistor M3 connected between a voltage reference line Vrst and the second sense node B; a second reset transistor M4 connected between the first sense node A and the second sense node B; and a buffer amplifier M1 having an input connected to the first sense node A. The control logic is arranged to operate the pixels in a low conversion gain mode and in a high conversion gain mode. In each of the conversion gain modes the control logic is arranged to operate one of a first reset control line RS1 and a second reset control line RS2 to continuously switch on one of the first reset transistor M3 and the second reset transistor M4 during a readout period of an operational cycle of the pixels.