An image formed when light rays travel outward from an optical system, causing the observer's eye to trace them backward to an apparent point of origin. Unlike a real image, the light does not physically converge at the location of the virtual image, meaning it cannot be captured on film or a sensor placed at that spot. The reflection seen in a standard flat bathroom mirror is the most common example.
You can't put a light meter on the virtual image because the photons aren't actually gathering there.
A virtual image is always upright relative to the object, whereas a real image is typically inverted.
Related terms
Virtual
Describing an optical point or image formed by the apparent divergence of light rays rather than their actual intersection.
Virtual focus
The point from which diverging light rays appear to emanate after passing through a negative lens or reflecting off a convex mirror.
Image
The optical reproduction of an object formed by light rays focused by a lens or mirror.