1. An image processing device comprising: an image acquisition section that acquires an image that has been acquired by imaging a tissue using an endoscope apparatus; an in vivo position identification information acquisition section that acquires in vivo position identification information that specifies an in vivo position of the endoscope apparatus when the image has been acquired; an in vivo model acquisition section that acquires an in vivo model that is a model of the tissue; an on-model position determination section that specifies an on-model position that corresponds to the position specified by the in vivo position identification information on the acquired in vivo model; and a linking section that links information about the acquired image to the specified on-model position.