YIQ
YIQ is the color space used by the NTSC color TV system, employed mainly in North and Central America, and Japan. It is currently in use only for low-power television stations, as full-power analog transmission was ended by the U.S. Federal Communications Commission (FCC) on 12 June 2009. It is still federally mandated for these transmissions as shown in this excerpt of the current FCC rules and regulations part 73 "TV transmission standard":
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