1. An image processing apparatus configured to generate a high resolution image having higher resolution than a plurality of low resolution images from the low resolution images, the image processing apparatus comprising: a target area setting unit configured to set a target area which is an area to be noted in each of the low resolution images; an image index estimating unit configured to estimate an image index representing a property of an image in the target area set in each of the low resolution images; and a selecting unit configured to select any of the low resolution images which are a reference for generating the high resolution image from the low resolution images depending on the estimated image index.