CIE Whiteness

Definition

The Commission Internationale de l’éclairage (CIE) whiteness formula was recommended in 1986 as an assessment method for white materials [1]. For the CIE 1931 standard colorimetric observer, the whiteness index W is given by

$$ W=Y + 800\ \left({x}_{\mathrm{n}}\hbox{--} x\right) + 1,\kern-0.15em 700\ \left({y}_{\mathrm{n}}\hbox{--} y\right), $$

(1)

where x, y are the chromaticity coordinates of the sample, and x _n, y _n are those of the illuminant. For the CIE 1964 supplementary standard colorimetric observer, the whiteness index W ₁₀ is given by

$$ {W}_{10}=Y + 800\ \left({x}_{\mathrm{n},\kern-0.15em 10}\hbox{--} {x}_{10}\right) + 1,\kern-0.15em 700\ \left({y}_{\mathrm{n},\kern-0.15em 10}\hbox{--} {y}_{10}\right), $$

(2)

where x₁₀, y₁₀ and x _n,10, y _n,10 are the chromaticity coordinates of the sample and the illuminant, respectively.

The tint coefficient T _w or T _w,10, given by the following formulae, is zero for a sample without reddishness or greenishness. For the CIE...