Eidetic and photographic memory, although slightly different concepts, generally refer to the ability to voluntarily recall or hallucinate viewed images with extreme detailed accuracy. Eidetic memory is the ability to voluntarily conjure a vivid mental image of a viewed scene, or object, including its color and textured spirit to a precise degree. These images are mentally projected in space as being sheer or transparent. Eidetic images are unlike ordinary images because the images do not change during eye movements and can be evoked for days to years after the original encounter with the specific scene.