rgb2lch: RGB to Cylindrical Color Space Conversion

Mathematical Transformation to Cylindrical Coordinates

RGB to LCH conversion transforms Cartesian color coordinates into cylindrical representation via LAB color space. The process separates luminance from chromatic information and expresses color relationships through polar coordinates.

The mathematical transformation sequence: $\text{LAB} = f_{\text{RGB}\rightarrow\text{LAB}}(\text{RGB})$ $\text{LCH} = \begin{bmatrix} L \\ \sqrt{a^2 + b^2} \\ \arctan(b, a) \cdot \frac{180}{\pi} \end{bmatrix}$

Where $L$ preserves lightness from LAB, chroma $C$ equals the magnitude of chromatic components, and hue $H$ represents the angle in degrees.

Cylindrical Representation Advantages

LCH coordinates provide intuitive color manipulation by separating achromatic and chromatic information. Lightness controls brightness independently of color content, chroma adjusts saturation, and hue rotates through the color spectrum.

Computational properties:

• Magnitude calculation: Chroma computed as Euclidean distance in ab plane
• Angular conversion: Hue derived from arctangent with proper quadrant handling
• Degree scaling: Angular result converted from radians to degrees for standard notation

ライブエディター

const fragment = () => {
      const rgbColor = vec3(uv.x, 0.5, uv.y)
      const lchColor = rgb2lch(rgbColor)
      const color = vec3(lchColor.x.div(100), lchColor.y.div(100), lchColor.z.div(360))
      return vec4(color, 1)
}