Determine YIQ Colour Model

Whereas an RGB monitor requires separate signals for the red, green, and blue components of an image, a television monitor uses a single composite signal. The National Television System Committee (NTSC) colour model for forming the composite video signal is the YIQ model.

In the YIQ colour model, luminance (brightness) information is contained in the Y parameter, while chromaticity information (hue and purity) is incorporated into the I and Q parameters. A combination of red, green, and blue intensities are chosen for the Y parameter to yield the standard luminosity curve. Since Y contains the luminance information, black-and-white television monitors use only the Y signal. The largest bandwidth in the NTSC video signal (about 4 MHz) is assigned to the Y information. Parameter I contains orange-cyan hue information that provides the flesh-tone shading, and occupies a bandwidth of approximately 1.5 MHz. Parameter Q carries green-magenta hue information in a bandwidth of about 0.6 MHz.