1. An image processing apparatus which is accessible to at least one storage device storing a first shelf image acquired by photographing, with a first camera, a display shelf for displaying a product, a second shelf image acquired by photographing the display shelf with a second camera from a direction that is different from that of the first camera, and an single item image acquired by photographing the product as a single piece with a known photographing distance, the apparatus comprising a processor configured to: receive the first shelf image, the second shelf image, and the single item image, estimate a separation distance from the first camera to the display shelf, based on the first shelf image and the second shelf image, determine a search distance, based on the estimated separation distance, generate a template image by converting a number of pixels of the single item image stored in the storage device, with a magnification corresponding to a ratio between the determined search distance and the known photographing distance, identify the product and an area of the product within a target area of the first shelf image based on similarity degrees between pixels of the first shelf image and the pixels of the template image.