CIELAB Color Space Explained: Device-Independent Color
RGB describes what a device does; CIELAB describes what a human sees. Defined by the CIE in 1976, LAB positions every color by L* (perceived lightness 0–100), a* (green ↔ red axis) and b* (blue ↔ yellow axis) — the opponent channels the visual system actually uses. Because it's anchored to human vision rather than any device, LAB is the hub through which serious color management converts everything else.
Why LAB matters
Delta E — the distance between two colors in LAB — is the industry-standard measure of color difference: ΔE below ~1 is invisible, 2–3 is barely visible, above 5 is obvious. Brand-color quality control, paint matching and display calibration all speak Delta E. LAB also enables meaningful operations like "same lightness, different hue" that RGB can't express.
| Channel | Axis | Range (typical) |
|---|---|---|
| L* | Black → white | 0 to 100 |
| a* | Green → red | −128 to +127 |
| b* | Blue → yellow | −128 to +127 |
Limitations and successors
LAB's blue region misbehaves — darkening a saturated blue shifts it purple — and its hue lines aren't perfectly straight. OKLab (2020) fixes these issues and now powers CSS color math. For intuitive polar editing of LAB, use LCH. Try it: RGB to LAB, LAB to RGB, LAB to LCH.