Certain aspects relate to systems and techniques for using imaging pixels (that is, non-phase detection pixels) in addition to phase detection pixels for calculating autofocus information. Imaging pixel values can be used to interpolate a value at a phase detection pixel location. The interpolated value and a value received from the phase difference detection pixel can be used to obtain a virtual phase detection pixel value. The interpolated value, value received from the phase difference detection pixel, and the virtual phase detection pixel value can be used to obtain a phase difference detection signal indicating a shift direction (defocus direction) and a shift amount (defocus amount) of image focus.