These amazing optical illusions have been created by Ukrainian artist Oleg Shuplyak.
Merging portraits of famous figures from art and fiction with landscapes and images from nature, his work requires a double take - or in some cases, several minutes of staring - before the secrets of the visual illusions reveal themselves.
Famous artists, cultural figures and characters to be given Shuplyak optical illusion treatment include John Lennon, Pablo Picasso, Sigmund Freud, Charles Darwin, Paul Gauguin, Zeus and Uncle Sam.
Each optical illusion reveals two separate images, some far quicker than others. But all display an extraordinary level of artistry and a playful take on classic imagery.
Shuplyak was born in 1967 in the Ternopol region of the Ukraine, and studied architecture at the Lviv Polytechnic Institute.
An optical illusion occurs when information absorbed by the eye is processed by the brain to give a perception that doesn't match the physical measurement of the source. There are three types: literal optical illusions like Shuplyak's, physiological optical illusions where a specific aspect of vision - such as brightness, colour or size - is exaggerated, and cognitive illusions which occur for unconscious reasons.
How many of Shuplyak's optical illusions can you make out, and which are your favourites?
See Oleg Shuplyak's optical illusion paintings in the gallery below.
Check out more of Oleg Shuplyak's optical illusions.