Why Do Most Paintings Look Flat?

When you look at a painting of a mountain, your brain knows it is just paint on wood. But why does it feel deep? This is because of the flat painting illusion.

Your eyes see things in 3D because they have two different views. A camera or painting only has one view like looking through a keyhole. Your brain gets confused but tries to fix it.

Artists paint tricks called depth cues. They make far away things look blue and small. They make close things big and bright. It is like a magic trick but with math.

Think of a cardboard box. It is flat until you open it. Painting is like opening your mind to see inside the box even though the front stays closed.