composite of equal quantities of red, green, and blue light. Therefore, to determine how much red, green or blue light is present in an image, one can develop a system that subtracts color (chrominance) information from luminance information. This is exactly what video coding systems do. There are many different variations but, essentially, they all rely on colordifferencing. Color differencing is the first step in encoding the color television signal. Subtracting the luminance information from each primary color forms the color difference signals: red, green, or blue. Color difference conventions include the SMPTE format, the Betacam format, the EBU-N10 format and the MII format. Color difference signals are not component video signals-these are, strictly speaking, the pure R, G, and B waveforms. There are two types of video signals, component and composite. In component video, the Y or luminance signal is recorded and transmitted separately from the C (hue and color saturation) signal. Because the luminance signal is recorded at a higher frequency, more resolution lines are available to it. Because the eye is less sensitive to chroma signals, those signals are recorded at lower frequencies and transmitted using less bandwidth. Component video is not a standard, but rather a technique. It results in greater signal control (keeping signals separate makes them easier to manipulate) and higher image quality. Component video is often called Y/C video. NTSC and PAL television systems use composite video. In composite video, brightness, hue and saturation are combined into a single signal. In its analog form, the chrominance signal is a sine wave that is modulated onto the luminance signal, which acts as a subcarrier. In NTSC systems, the YIQ trichromatic color system is used. The two color differences are first combined, using a technique known as quadrature modulation. Next, this color information is modulated onto the 4.5 MHz Y subcarrier with the phase of the sine wave describing the color itself and the amplitude