Purple is a variety of colors with a hue between red and blue. In the RGB color model used on computer displays and televisions, shades of purple are created by mixing red and blue light. In the RYB color model historically used by painters, violets are created using a combination of red and blue pigments. In the CMYK color model used in printing, purple colors are obtained by combining the magenta pigment with the cyan pigment, the black pigment, or both. Purple has long been associated with royalty, originally because Tyrian purple tincture, made from the mucus secretion of a species of snail, was very expensive in ancient times. Purple was the color worn by Roman magistrates; It became the imperial color worn by rulers of the Byzantine and Holy Roman Empires, and later by Roman Catholic bishops. Even in Japan, the color is traditionally associated with the emperor and the aristocracy. According to contemporary surveys in Europe and the United States, purple is the color most commonly associated with strangeness, royalty, magic, mystery, and divinity. Associated with pink, it is associated with eroticism, femininity and seduction.