1. An image processing apparatus comprising: a computer programmed to: acquire significant pixel regions shown in an image in which at least one object and at least one marker are shown; discriminate the significant pixel regions as one of the object's region and the marker's region in accordance with a predetermined criterion; acquire indicated-position information on the basis of the marker in the image; acquire reference position information including a position of the object in the image and a position of at least one of a plurality of vertices of a target region of the image, the target region being formed to be a multangular shape having the plurality of vertices; partition the target region of the image on a basis of the reference position information to generate a plurality of partition regions; identify at least one partition region on a basis of the plurality of partition regions and the indicated-position information; and determine whether the object has been selected, on a basis of the identified partition region.