YIQ
YIQ (Y for luminance, I for in-phase and Q for quadrature), like YUV, is a color space used in television signals. YIQ is used predominantly by the NTSC television standard for encoding color information. The Y component, like in YUV, is used to encode luminance information, and is the only component used by black-and-white television receivers. The I and Q signals contain the actual color information. The YIQ color space is actually exactly the same as YUV, except the I-Q plane differs from the U-V plane by a simple 33-degree rotation. This rotation puts one of the two color axes in the orange region of the color space, which is where flesh tones are found.
A formula exists for converting colors from the RGB color space to YIQ. This formula, where R, G, and B are defined on a scale from zero to one, is shown below.
- Y = 0.299 R + 0.587 G + 0.114 B
- I = 0.596 R - 0.275 G - 0.321 B
- Q = 0.212 R - 0.523 G + 0.311 B
