YIQ was a color space used in the NTSC television standard which has now turned obsolete. I stands for intermodulation, while Q stands for quadrature. NTSC now uses the YUV color space, the same as in PAL and other systems. A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components (e. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Example of U-V color plane, Y value = 0. ... For other meanings of PAL see PAL (disambiguation). ...

The Y component represents the luminance information, and is the only component used by black-and-white television receivers. I and Q represent the chrominance information. In YUV the U and V components can be thought of as x and y coordinates within the colorspace. I and Q can be thought of as a second pair of axes on the same graph, rotated 33° from V and U, respectively. Thus, I and Q are simply another way of locating a point in the U and V plane. The word luminance, a synonym for luminosity, means emitting or reflecting light. ... Chrominance (chroma for short) comprises the two components of a television signal that encode color information. ... Example of U-V color plane, Y value = 0. ...

The reason for doing this is to take advantage of a trait of the human eye. It is more sensitive to changes in the orange-blue (I) range than in the purple-green range (Q). Thus less bandwidth is required for Q than for I. Broadcast NTSC limits I to 1.3 MHz and Q to 0.5 MHz, which keeps the bandwidth of the overall signal down to 4.2 MHz. In YUV systems, since U and V both contain information in the orange-blue range, both components must be given the same amount of bandwidth as I to achieve similar color fidelity.

True I and Q decoding in television receivers is rare due to the costs of implementation, with only a handful of TV sets made.

Formula

This formula approximates the conversion from the RGB color space to YIQ. R, G and B are defined on a scale from zero to one: The RGB color model utilizes the additive model in which red, green, and blue light are combined in various ways to create other colors. ...

or using matrices

Two things to note:

• The top row is identical to that of the YUV color space
• If then . In other words, the top row coefficients sum to unity and the last two rows sum to zero.

Example of U-V color plane, Y value = 0. ...

See also

• Color space:
  • RGB color model commonly used for color monitors
  • CMYK color model for color printing
  • HSV color space
  • HLS color space
  • RYB color model the traditional color model used by artists.
  • YUV for PAL television