Perception is everything

In the presentation  Beau Lotto talks about how optical illusions effect everything we perceive which makes us ask the question what  is real ? For example if there is a red poster on the wall two people will agree that's the posters red but the two people don't actually see the exact same color. Everyone has a different perception of everything and everyone around them.Beau Lotto continues to explain how this can be used against people to manipulate what they see or how they perceive it. This is used in advertisements to convince the human mind into wanting there product. The producer of a add can put things in the background of his add to enhance the product and draw in the viewer they can add any detail they want to improve sales. So if all of us see everything different and nothing that we see is truly what it seems what is real ?