iming of the rotation was such that a colored sector appeared in front of the lens for exactly one field. The resulting sequence of fields corresponded to the color components in the image. At the television receiver, synchronized with the color field, another color- filter disk rotated in front of the picture tube. The system was bulky, noisy, and prone to wear. It required exact synchronization between the rotating filter and the fields presented on the picture tube; mis-timing would cause a color shift. However, the biggest problem with field-sequential color was incompatibility with the monochrome system of the day. The color system generated 24 fps rather than the monochrome system's 30, and (like European systems) it generated 405 scanning lines rather than the monochrome system's 525. To identify a solution, they established, in 1950, the National Television Systems Committee (NTSC). Three years later, in December 1953, the NTSC defined a color- telecasting standard that was compatible with the monochrome system. The standard, over time, has changed how Americans view the world. FROM LIGHT WAVES To BRAIN WAVES To understand the NTSC system of color telecasting, it is helpful to understand how eyes process light. Simply stated, eyes capture patterns of light and send them to the brain for interpretation. Television exploits the eyes' properties and is patterned after them. The human eye's structure is similar to that of a camera. At the front of the eye is the transparent cornea. It captures a picture of the outside world and forms an image. Behind the cornea is the iris, a circular muscle that expands and contracts to control the amount of light that enters the eye. It is similar to a camera's automatic exposure system. The lens focuses an image by changing shape to accommodate differences between close and distant subjects. Behind the lens is a fluid-filled compartment on the surface of which is the retina. The retina consists of more than one hundred million tiny photoreceptors called rods and cones. Rod