1. An image processing apparatus comprising: a generation unit configured to generate a subtraction image between a plurality of fundus images of an eye corresponding to a plurality of three-dimensional tomographic images obtained by capturing images of the eye at different times; a display control unit configured to control a display unit to display the subtraction image; and a specifying unit configured to specify a plurality of two-dimensional tomographic images, in the plurality of three-dimensional tomographic images, to be displayed on the display unit, by a position specified on the displayed subtraction image.