The Importance of a Flat Smooth Surface in Optics

In optics an image is just well it's something that we see but let's try and make that concept a bit more explicit. An image is formed when all of the light from a given object or a given point on an object in the real world in the environment converges at a single point in an image. In order for an image to occur any type of image you have to have sort of a one to one mapping light from one part of an object goes to one part of the image. But what's the difference between a real and a virtual image? Well a real image is when the light really does converge like that in other words if you put a piece of paper there you could