See your true colors.
The average human eye can distinguish over 10 million different colors, but some people can see many, many more. A rare genetic trait, tetrachromacy, allows certain people to see far more colors than others due to additional pigment in their eyes.
The average person's eye cells contain three cones that trigger wavelengths of light to display color. Tetrachromats have a fourth cone in their eyes, offering them the ability to distinguish hundreds of millions of additional colors.
© VICTOR DE SCHWANBERG/Science Photo Library/Corbis