A pixel structure comprises a photo-sensitive element for generating charge in response to incident light. A first transfer gate is connected between the photo-sensitive element and a first charge conversion element. A second transfer gate is connected between the photo-sensitive element and a second charge conversion element. An output stage outputs a first value related to charge at the first charge conversion element and outputs a second value related to charge at the second charge conversion element. A controller controls operation of the pixel structures and causes a pixel structure. The controller causes the pixel structure to: acquire charges on the photo-sensitive element during an exposure period; transfer a first portion of the charges acquired during the exposure period from the photo-sensitive element to the first charge conversion element via the first transfer gate; and transfer a second portion of the charges acquired during the exposure period from the photo-sensitive element to the second charge conversion element via the second transfer gate.