1. An image processing apparatus comprising: an identification unit configured to identify a retinal blood vessel based on a first retinal image; a measurement unit configured to measure blood flow information for the blood vessel based on the first retinal image; and a blood vessel depth position determination unit configured to determine a depth position of the blood vessel based on a second retinal image; and a display control unit configured to display the measured blood flow information by at least one selected from the depth position of the identified blood vessel, a size of the identified blood vessel, and a combination of both.