The human eye can see millions of colors. However, it won’t always distinguish colors from one another accurately. You may perceive two slightly different colors as the same or see differences in objects of identical color depending on your viewing angle and lighting. This creates challenges when communicating about color.
To reproduce an exact desired color every time, manufacturers and designers need ways to quantify a color’s properties and determine the numerical difference between shades. CIELAB or CIE L*a*b* is a device-independent, 3D color space that enables accurate measurement and comparison of all perceivable colors using three color values. In this color space, numerical differences between values roughly correspond to the amount of change humans see between colors.
What Is L*a*b*?
The International Commission on Illumination (CIE) developed the L*a*b* color model in 1976 with the intent of creating a standard for color communication. When creating the CIELAB color space, the CIE drew inspiration from the CIE 1931 XYZ color space, as well as the Munsell color system. All of these models use three data points to define and plot a color.
CIE developed CIELAB to simplify color communication regardless of the device used. The color space is copyright- and license-free, which means you can use it freely and integrate it into any device or system. As a result, organizations in many industries use CIELAB to control color and define color tolerance standards.
What Does CIE L*a*b* Stand for?
The CIE in CIELAB is the abbreviation for the International Commission on Illumination’s French name, Commission Internationale de l´Eclairage. The letters L*, a* and b* represent each of the three values the CIELAB color space uses to measure objective color and calculate color differences. L* represents lightness from black to white on a scale of zero to 100, while a* and b* represent chromaticity with no specific numeric limits. Negative a* corresponds with green, positive a* corresponds with red, negative b* corresponds with blue and positive b* corresponds with yellow.
How CIE L*a*b* Calculates Color
The CIELAB color space uses measurements of a color’s L*, a* and b* values to plot its location on a chart that contains an infinite number of possible colors, including colors outside the visible light spectrum. Using the values on the L*a*b* chart, you can use calculations to quantify the difference between specific colors, which is referred to as Delta (Δ). To calculate ΔL*, for example, you need to subtract the standard color’s L* value from the sample’s L* value. You can also use L*a*b* values to convert to a different color scale.
Before you can perform any L*a*b* calculations, you need to determine the sample’s L*, a* and b* values. To do this, you will need to use spectrophotometry instrumentation. Instruments gathering CIELAB data will usually view the sample at a 2- or 10-degree angle.
Learn More About Measuring Color
Color models such as the CIELAB color space make it easier for manufacturers and designers to communicate color specifications accurately and produce products with color consistency. At HunterLab, we offer color measurement instruments to help you take advantage of this universal color space. Contact us today for more information about how our spectrophotometers could help you measure color.
Mr. Philips has spent the last 30 years in product development and management, technical sales, marketing, and business development in several industries. Today, he is the global market development manager for HunterLab, focused on understanding customer needs, providing appropriate solutions and education, and helping to solve customer color challenges across these industries and cultures.