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

equal amounts at all visible wavelengths, as seen in Figure 3.8. Contrast this with
the distribution of energy from a fluorescent light bulb, where there are relatively
large peaks in the lower and central wavelengths (blue and green, respectively).
This is why photographs taken inside under fluorescent light often have the charac-
teristic of being slightly more greenish-blue than pictures taken in natural lighting.
Figure 3.8: Intensity of the D65 illuminate (typical average daylight) and
fluorescent light over the visible spectrum. Adapted from [G95b].
In order to quantify the physical energy of the spectral distributions of emissive
light sources, one must integrate the illuminant’s energy over all wavelengths. In
discrete math, the energy reaching the eye at all wavelengths from emitted light,
P =
λ E(λ), where E(λ) is the emitted light energy at each wavelength.
Light does not only reach the eye via emitted light, but also from reflections.
The perception of light reflected from the surface is dependent on both the re-
flectance properties of the material and the given light source. Therefore, changes
in lighting will affect the perceived appearance of an object. Artists attempt to
work under similar lighting conditions to that of the environment where the art
will be exhibited, save encountering problems in hue shifting.
Physically, the energy reaching the eye at all wavelengths from reflected light,
P =
λ E(λ)R(λ), where R(λ) is the reflected light energy at each wavelength.
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