1. An image processing device, comprising: a data storage unit storing feature data indicating a feature of appearance of an object; an environment map generating unit for generating an environment map representing a position of one or more objects existing in a real space based on an input image obtained by imaging the real space using an imaging device and the feature data stored in the data storage unit; and an output image generating unit for generating an output image obtained by erasing an erasing target object from the input image based on a position of the erasing target object specified out of objects present in the input image represented in the environment map and a position of the imaging device.