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LCH Color

About LCH Color

LCH color is a color space that represents colors with lightness, chroma, and hue. It uses the same perception-based idea as Lab color, but represents the color tone with chroma and an angle, making color strength and hue easier to adjust separately.

ComponentMeaningExample value
L: LightnessRepresents the brightness of the color. 0% is black and 100% is white.60%
C: ChromaRepresents the strength of the color. 0 is achromatic, and larger values produce more vivid colors.80
H: HueRepresents the color tone as an angle.90deg

For example, major colors such as red can be represented as follows.

ColorLCH notationRGB notation
Redlch(54.29% 106.8372 40.86deg)rgb(255 0 0)
Greenlch(46.28% 67.9842 134.38deg)rgb(0 128 0)
Limelch(87.82% 113.3315 134.38deg)rgb(0 255 0)
Bluelch(29.57% 131.2014 301.36deg)rgb(0 0 255)
Whitelch(100% 0 0deg)rgb(255 255 255)
Blacklch(0% 0 0deg)rgb(0 0 0)

To include transparency, add an alpha value. For example, semi-transparent red can be represented as lch(54.29% 106.8372 40.86deg / 0.5).

Handling of lightness, chroma, and hue

Lightness is handled in the range from 0% to 100%. Values below 0% are treated as 0%, and values above 100% are clamped to 100%.

Chroma is handled as a value of 0 or greater. Negative chroma is handled as 0. When chroma is 0, the color becomes achromatic and hue is handled as 0deg.

Hue is handled as an angle, and values greater than 360deg or negative values are normalized to the range from 0deg to 360deg. For example, lch(54.29% 106.8372 400.86deg) is handled as the same color as lch(54.29% 106.8372 40.86deg).

Difference between LCH and Lab

Lab represents colors with the rectangular coordinates a and b. LCH converts the color tone to chroma and hue. Therefore, LCH can be more intuitive when you want to adjust chroma or hue while keeping the same lightness.