1. A method of operating an imaging system having an array of pixels arranged in rows and columns, wherein each pixel comprises four adjacent photosensitive areas located in two adjacent columns and two adjacent rows, and wherein each pixel comprises a microlens that covers the four adjacent photosensitive areas, the method comprising: generating image signals in the four adjacent photosensitive areas of each pixel; processing the image signals of each of the four adjacent photosensitive areas of at least one pixel to determine phase information; and processing the image signals of each of the four adjacent photosensitive areas of the at least one pixel to determine image information.