1. An image processing apparatus comprising at least one processor to implement: an information obtainer configured to obtain an image created by photographing a region of interest and location information indicating a location from which the image is photographed; a density map generator configured to generate a crowd density map of the image based on crowd density information estimated from the image; a perspective map generator configured to generate a perspective map that provides distance information indicating a real-life distance between two points in the image based on the location information; and a heat map generator configured to generate a heat map that displays the crowd density map on a map of the region of interest based on the distance information, wherein the density map generator is further configured to: split the image into patch images respectively representing different parts of the region of interest, the different parts being of a same real-life size, estimate a crowd density class of each of the patch images based on characteristic information extracted from each of the patch images, and estimate the crowd density information based on the crowd density class.