Depth and space

If you look at a photo, you actually see flat figures, as in the allegory of Plato's cave. The chained ones only saw shadows of people and objects on the wall and had no idea of the real, spatial world.The myth of the cave, Politeia. (380 BC)

A photo also only suggests depth or space and is not much more than a flat distorted representation on the wall. With my experience of the real world however I can imagine and understand what I see in the photo. That's what my brain does.