LCh color space
The CIE-LCh color space is the CIELab color space , whereby instead of the Cartesian coordinates a * and b *, the cylinder coordinates C * (relative color saturation , English chroma , chromaticity ' ) and h ° ( English hue angle , hue angle' ) must be specified. The color brightness L * ( English lightness 'brightness' ) remains unchanged.
The simplified notations LCh , LCH and HLC (hue H - lightness L - saturation C) are common for this color space .
Coordinate transformation
The conversion of a * and b * in C * and h ° is performed according to the following formulas:
Conversely, the polar coordinates can be converted into the Cartesian coordinates:
The value for the brightness L * remains.
Demarcation
The LCh color space is not identical to the HSV , HSL or HSB color space . Their values can also be interpreted as the base color H, saturation S and brightness of a hue, but are derived from a polar coordinate transformation of the technically defined RGB color space and are therefore only slightly perceptual .
For example, H and h are not identical, since the HSL space uses three colors as the basic color (additive primary colors red, green, blue with hue angle H = 0 °, 120 °, 240 °), but the LCh system uses four colors ( color-physiological elementary colors Red, yellow, green, and blue with h = 0 °, 90 °, 180 °, 270 °). h = 0 is the case for achromatic colors on the gray axis .
Individual evidence
- ↑ In the variety of color systems, hue, lightness and saturation are logical quantities . In: FARBImpulse, May 10, 2006.