Digital Prints

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Mastering Digital Printing
Figure 4.4 The spectral curves of two standard CIE Illuminants (A is for tungsten or incandescent, D or more specifically D65 is a
standard daylight source) and a popular fluorescent or F source.
Courtesy of GretagMacbeth
metamerism as: When two different color objects have the same color appearance to a normal
human viewer under one light source (metameric match) but look different under
another light source (metameric mismatch).
Since the light source has a major impact on how the colors are perceived, the light along
with the object and the human observer form the triumvirate of what we know as color.
See more about light sources and viewing in the “Room with a View” box.
Measuring Color
With standard light sources and a model of human vision, we can measure and quantify the
light spectra that form colors in our minds by using one of these three measuring devices:
Densitometers compute density by directing light onto a surface and measuring the
amount of light returned through filters. They don’t read color directly but can calculate
relative densities of color patches. Not commonly used by photographers-artists except in
certain situations.
Colorimeters measure light through filters like densitometers, but the filters and the internal
circuitry match human vision much more closely. “Colorimetry” standardizes two of
the three color variables (light source and observer) and then works with the third (object).
Colorimeters are frequently used for monitor profiling (see below).
Spectrophotometers, also called “spectros,” measure the full light spectrum in even more
detail than colorimeters. Either handheld or adaptable to mounting tables or with suction
cups, spectrophotometers can measure reflective prints, and in some cases, monitor displays
and transmissive film. Spectros (including the related spectrocolorimeters) are often
used in higher-end profile-generating packages.