Since human color perception is subjective, there are colorimeters for the exact color determination of emitting and reflecting colors. They are based on various color models such as the Lab color model or the FCH color model and can determine brightness, color saturation and hue.
Color measuring devices, colorimeters, are used in industry, trade, commerce and the printing industry, as well as in quality control, architecture, design and the paint industry. Color measurements are particularly problematic due to the fact that subjective human color perception does not correspond to theoretical color models, and these deviations are very pronounced for certain colors and color mixtures. In addition, for color measurements on reflecting bodies, the color of the illumination is decisive. In the printing industry, a light source that emits daylight is used for this purpose. In colorimeters, the standardized illumination conditions are generated by a built-in light source. The CIE standard illuminants C or D65 are used.
Colorimeters capture the colors to be measured with a CCD sensor or CMOS sensor and filter the captured light according to the color sensitivity of the human eye. The measured signals are transmitted to a microcomputer, which calculates the numerical measurement results and displays them on a screen. The measurement results are also stored and can be used for quality comparisons with other measurement results. In a visual inspection, on the other hand, human inspectors would have to detect the smallest color differences and assess whether the color differences are still within the specified tolerances.