1. An image processing method comprising: a physical image acquisition step of acquiring an image of a physical space; a viewpoint position/orientation acquisition step of acquiring a position/orientation of a viewpoint; a virtual image generation step of generating an image of a virtual space according to the position/orientation the viewpoint using virtual object information; a detection step of detecting a specific object area; a masking process step of applying a masking process to the image of the virtual space in accordance with the detected object area; a composition step of compositing the image of the physical space and the image of the virtual space to which the masking process has been applied; and a control step of controlling the masking process in accordance with the masking process control information included in the virtual object information.