How to Convert LCH to HSL
Converting LCH to HSL moves a color from an absolute, perceptually uniform cylinder into a relative, mathematically flawed cylinder. While LCH is superior for color accuracy, HSL is often required for legacy systems or specific design tools.
Comparing the Cylinders
Both formats use a Hue angle (0-360°), but they handle lightness and intensity very differently.
- Lightness: In LCH, lightness is absolute. A lightness of 50 is exactly halfway between black and white to the human eye. In HSL, lightness is relative to the hue. When converting from LCH to HSL, the lightness percentage will often change drastically to accommodate the flaws in the HSL model.
- Intensity: HSL uses Saturation, a strict 0-100% scale. LCH uses Chroma, which represents the actual amount of color present and is theoretically unbounded (often reaching 130 or higher for vibrant colors).
The Conversion Process
There is no direct path between LCH and HSL. The conversion requires translating the LCH color into CIELAB, converting that to the CIE XYZ reference space, transforming it to linear RGB, applying gamma correction to get standard sRGB, and finally calculating the Hue, Saturation, and Lightness from those RGB channels.