Vermilion is a brilliant red or scarlet pigment originally made from the powdered mineral cinnabar, and is also the name of the resulting color. It was widely used in the art and decoration of Ancient Rome, in the illuminated manuscripts of the Middle Ages, in the paintings of the Renaissance, and in the art and lacquerware of China, where it is often called "Chinese Red". In art and culture File:Villa of Mysteries (Pompeii)-20.jpg|The bright vermilion murals in the Villa of Mysteries in Pompeii (before 79 AD) were painted with ground and powdered cinnabar, the most expensive red pig...

Impossible colors or forbidden colors are hues that cannot be perceived by ordinary viewing conditions from light that is a combination of various intensities of the various frequencies of visible light. Examples of impossible colors are bluish-yellow and reddish-green. These colors include "Stygian blue" (an impossible deeply saturated blue-black) and "hyperbolic orange" (an orange color that is oversaturated compared to a pure spectral orange). Opponent process The color opponent process is a color theory that states that the human visual system interprets information about color by pr...

Binocular rivalry is a phenomenon of visual perception in which perception alternates between different images presented to each eye. When one image is presented to one eye and a very different image is presented to the other (also known as dichoptic presentation), instead of the two images being seen superimposed, one image is seen for a few moments, then the other, then the first, and so on, randomly for as long as one cares to look. For example, if a set of vertical lines is presented to one eye, and a set of horizontal lines to the same region of the retina of the other, sometimes th...