A sensed image generated from an image signal output from an image sensor for receiving light that becomes incident sequentially through an imaging lens and a microlens array that is a two-dimensional array including a plurality of microlenses is acquired. A list is created in which, for each pixel position on the image sensor, the correspondence between the coordinates of the light incident at the pixel position on the imaging lens and the coordinates of the pixel position is registered. Images obtained by rearranging pixels at the coordinate positions on the image sensor corresponding to the coordinates in accordance with the arrangement order of the coordinates on the imaging lens are generated as a parallax image group.