1. An image processing method for combining a virtual image with a shot image to obtain a combined image and displaying the combined image, the image processing method comprising: capturing a shot image picked up by an image-pickup unit; extracting a predetermined region from the shot image with an extracting unit; generating a virtual image based on a transparency parameter based on a ratio of the size of the predetermined region to the size of the shot image; combining the virtual image with a region of the shot image excluding the predetermined region to obtain a combined image; and displaying the combined image.