抄録
The expression for the color-difference line elements in a uniform color space in cylindrical co-ordinates as is the case of the Munsell system is modified to conform to the hyperbolic geometry as
Δs2=Δr2+(1+_??_)_??_Δθ2+Δz2
where r is the distance from the light source to the sample on the MacAdam (u, v) diagram, and for practical use it is rewritten as
ΔE={[106_??_1/2(_??_+_??_|_??_|2)]+[10Δ(vY)]2}1/2
In spherical coodinates as is the case of the DIN color system, the above expression becomes
Δs2=Δr2+g1(r)_??_Δθ2+g1(r, θ)_??_sin2θΔφ2
For determination of the functional forms of g1(r) and g2(r, θ), psychophysical experimental data on the color-difference are lacking.