Colorimetry

Abstract

We live in a very colorful world. Modern materials provide us with products in a multitude of colors that could only have been dreamt of in the past. Scientist and technicians use colorimetry, the measurement of color, to ensure that consumers get the colors that they are expecting to get consistently over time. In colorimetry, we try to simulate the human experience to quantify and control color. Color perception depends upon the light source illuminating an object, the pigments and dyes used in manufacturing the object, the eye of the observer whose impulses are translated by the brain as a color. To simulate color perception, standardized illuminants (mathematical light sources) were defined and color‐matching functions (simulating the eye‐brain combination) were experimentally derived. Spectrophotometers are used to characterize objects. An object may absorb light, scatter and reflect light, and/or transmit light. Spectrophotometers measure the reflectance and/or transmittance of the object at given wavelengths of the visible spectrum. Perceptual color coordinates of the object can be calculated for the spectrophotometric measurements. Colorimeters determine color coordinates directly during the measurement using broadband spectral devices. Special techniques are required to measure fluorescent samples that not only reflect light but emit light. Measuring materials containing traditional colorants and metallic flakes require instruments with multiple viewing angles. Measuring materials containing interference pigments require instruments with multiple illumination angles and multiple viewing angles. Measuring lamps and other light emitters require spectral radiometers and radiometric colorimeters.