Variations of the Fechner wheel.
The Fechner wheel is a disk that is printed in black and white. When the Fechner wheel spins at an appropriate speed, semicircles on the wheel appear to be in color. Modern computer technology makes it possible to rapidly and repeatedly present a series of images on a monitor screen. A series of still images of a Fechner wheel can be substituted for a Fechner wheel on a motor shaft. Straight lines and lines of text can be substituted for semicircles to obtain a color effect. A color effect can be obtained in small areas of black-and-white pictures.