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rgb2yiq: RGB to NTSC Color Space Conversion

Mathematical Structure of NTSC Color Encoding​

RGB to YIQ conversion transforms color values into the NTSC broadcast standard, separating luminance from quadrature-modulated chrominance components. This encoding enabled color television transmission compatible with black-and-white receivers.

The mathematical transformation: YIQ=MRGB→YIQ⋅RGB\text{YIQ} = M_{\text{RGB}\rightarrow\text{YIQ}} \cdot \text{RGB}

Where Y preserves luminance information, I encodes orange-cyan color differences, and Q encodes green-magenta color differences.

Quadrature Chrominance Encoding​

The I and Q components represent chrominance along axes rotated 33 degrees from the U and V axes used in other color spaces. This rotation aligned chrominance axes with principal directions of human color vision.

Mathematical properties:

  • Luminance weighting: Y component uses NTSC standard coefficients
  • Rotated chrominance: I and Q axes optimized for visual perception
  • Broadcast compatibility: Grayscale information preserved in Y component
ライブエディター
const fragment = () => {
      const rgbColor = vec3(uv.x, 0.7, uv.y)
      const yiqColor = rgb2yiq(rgbColor)
      return vec4(yiqColor.mul(0.5).add(0.5), 1)
}