Function Signature

js

xyzToLab(X: number, Y: number, Z: number): { L: number, a: number, b: number }

Parameters

X (number): The X tristimulus value relative to D65 reference white.
Y (number): The Y tristimulus value relative to D65 reference white.
Z (number): The Z tristimulus value relative to D65 reference white.

Return Value

An object representing Lab components: L (lightness, 0–100), a (green–red axis), and b (blue–yellow axis).

js

xyzToLab(48.4, 30.3, 4.0);
// { L: ~62, a: ~58, b: ~70 }

xyzToLab(35.8, 41.4, 98.5);
// { L: ~66, a: ~-7, b: ~-41 }

Conversion Details

Uses the D65 reference white (Xn=95.047, Yn=100.0, Zn=108.883).
Applies a piecewise function f(t) to normalize XYZ values:
f(t) = t^(1/3) if t > 0.008856, otherwise 7.787 * t + 16/116.
L = 116 * fy - 16
a = 500 * (fx - fy)
b = 200 * (fy - fz)

Examples

js

// Convert white reference
console.log(xyzToLab(95.047, 100.0, 108.883));
// { L: 100, a: 0, b: 0 }

// Convert black
console.log(xyzToLab(0, 0, 0));
// { L: 0, a: 0, b: 0 }

Error Handling

If any of the parameters are not numbers, the function returns { L: 0, a: 0, b: 0 }.

Usage Notes

Lab values are device-independent and useful for perceptual comparisons.
Commonly used with rgbToLab and labToRgb for conversions between RGB and Lab.
Supports ΔE (color difference) calculations when paired with another Lab value.