pigmented colorants: dependence on media and time - Cornell ...

Figure 3.18: XYZ Color Matching Functions. Notice that all of the
spectra are positive, therefore the three primaries can match any visible
color. Adapted from [GM97].
A natural way to discretize Equation 3.2 is to define a discrete sequence of
wavelengths, λi = λ0 + i∆λ for 0 ≤ i ≤ n − 1. A simple Riemann sum is used to
approximate the integral:
where
n−1
X = k P (λi)¯x(λi)
i=0
n−1
Y = k P (λi)¯y(λi)
i=0
n−1
69
Z = k P (λi)¯z(λi) (3.3)
k =
i=0
100
n−1 i=0 E(λi)¯y(λi)
Though the Riemann sum is the simplest method of discretizing integrals, there
are other methods such as Simpson’s rule or Gaussian quadrature. A graphical