CIELAB / CIELCh(ab)
Two views of the same device-independent color space: LAB uses opposing color axes, while LCh turns them into chroma and hue.
See it
What it is
CIELAB is a device-independent color space the CIE introduced in 1976. L* tracks lightness from black toward white, a* runs roughly from green to red, and b* from blue to yellow. CIELCh(ab) is the same space written as a cylinder: L* for lightness, C* for chroma, and h for hue angle. No color information changes when you switch between the two forms.
Reach for LAB when you need to measure color difference, convert between devices, or adjust lightness separately from colorfulness. Photoshop has shipped a Lab Color mode since the early 1990s, Delta E formulas are built on LAB, ICC color workflows use it as a connection space, and CSS exposes the family through lab() and lch().
Gotcha: LAB is more perceptually even than raw RGB, but it is not perfectly uniform. Equal numeric moves can still look different in different regions. The reference white matters too: CSS lab() uses D50, while sRGB uses D65, so a correct conversion needs chromatic adaptation instead of simply reusing the channel numbers.
Ask AI for it
Convert this sRGB palette to CIELAB and CIELCh(ab). Decode the sRGB channels to linear light, convert through XYZ, and use Bradford chromatic adaptation from D65 to the D50 reference white used by CSS lab() and lch(). Output both coordinate sets, CSS lab() and lch() values, and the CIEDE2000 Delta E between every adjacent swatch. Flag any pair below Delta E 2 as difficult to distinguish.