This invention has as its object to eliminate sensitivity nonuniformity on the plane of an image sensing element irrespective of exchange of a lens. Accordingly, printing quality deterioration of an image data having high frequency stemming from a lossy compression can be prevented, a processing speed increases since compression efficiency increases, providing convenience in use, and a production cost decreases since the image forming apparatus does no longer require a storage medium of large capacity. As a next step, the surface provided with these structures is modified by selectively removing protrusions by means of a micro-device. The attachment portion is configured to detachably engage with a sensor disposed outside the shell and operable to measure concentration of carbon dioxide gas expired from the nostrils.