Spectrophotometers are a common tool in nearly every industry, yet this valuable technology is often underutilized. Companies buy color measurement equipment out of necessity, then find themselves limited to the bare minimum of applications to get the job done. Understanding tristimulus values and the different geometric degrees and angles can be overwhelming, making instrument selection challenging. Well, not anymore! In this article, we provide a straightforward explanation of tristimulus value and color measurement, and provide resources to help you choose the right instrument for your application needs. Finding the support you need to use your color measurement tools correctly and effectively will ensure you get great value for your investment.
Human eye technology and color measurement
Spectrophotometers use technology from the human eye to create accurate, objective, and quantifiable measurements of color. These values can then be repeated to ensure color quality and consistency in product development. Based on human visual perception, color measurement relies on a system of three color values called tristimulus values. This system mirrors the color receptors in the human eye called cones. Tristimulus values measure light intensity based on three primary color values (RGB) typically represented by X, Y, and Z coordinates. The tristimulus value system is the basis of the color language, also known as the CIE color system, used to convey accurate color values around the world.
Other Factors Affecting Color Measurements
Tristimulus values are the basis for color measurement, but many other factors also affect color perception. Changes in light source, viewing angle, and field of view alter vision. Therefore, color Measurement Instruments need to be designed to take these variables into account. The standard field of view is the CIE 10-degree standard observer, which has been shown to be an accurate viewing degree that matches human visual perception. All stimulus values are calculated from this standard degree of observation, so manufacturers can be confident that exact color specifications will be met. Calculations are based on XYZ tristimulus values, depending on the illumination and reflectance type of the sample.
Color matching and quality regulations
Tristimulus values provide a reliable system that provides manufacturers and customers with a means of communicating color preferences to ensure accurate color matching and product compatibility. The ISO (International Organization for Standardization) uses these specific methods and the three-color value system to regulate and ensure compatibility standards between industries. Understanding the basics of color measurement is the first step to getting the most out of your color Measurement Instrument.
