Can you see a saxophone player in this image, or a girl’s face?
Your clever brain takes short-cuts and decides what you most likely want to see.
In this optical illusion, your brain makes a decision between the negative and positive light used to create the image. The musician is a silhouette, facing sideways and playing what appears to be a saxophone.
The girl’s face is facing forwards and is starkly lit, with the eyes, nose and mouth in shadow. Her nose and mouth are the musician’s fingers as he plays.
The top of her head is fragmented, making it difficult for your brain to interpret at first glance so you might see the prominent nose of the musician instead.