Image processing method, program, and image processing device

A visualization of choroidal blood vessel size is created.A vortex vein position is detected from a choroidal vascular image in which choroidal blood vessels have been visualized. Image processing is employed on the choroidal vascular image to extract first size choroidal blood vessels of a first size and to extract second size choroidal blood vessels of a second size different to the first size from the choroidal vascular image. A size analysis fundus image is generated in which a rectangular frame indicating the vortex vein position is displayed superimposed on the choroidal vascular image, and in which the first size choroidal blood vessels are displayed in red and the second size choroidal blood vessels are displayed in blue.