In optics, the image of an object is defined as the collection of focus points of light rays coming from the object. A real image is the collection of focus points made by real converging rays, while a virtual image is the collection of focus points made by backward extensions of real diverging rays. A virtual image is found by tracing real rays, that emerge from an optical device, backward to perceived or apparent origins of real ray divergences. In other words, a virtual image point is from which the real rays appear to be emitted.