Key Things to Look For in Color Instrumentation

From fan decks and paint chips to smartphone cameras and virtual painting apps, a multitude of color matching methods exist. Our State of Color Measurement series unpacks how the industry is changing, discusses the best tool out there, and uncovers where color measurement is going.

Effective Color Instrumentation: 5 Things to Consider in Color Measurement

The world of color measurement is quickly evolving, making it difficult to judge the quality of the many color measurement instruments on the market. Some instruments stand-alone, others offer compatible apps and cloud storage, and many make for tempting purchases, promising low price points, and color matching capabilities.

While there are many device specifications to consider, there are 5 key specifications that directly impact color measurement performance.

1.Inter-instrument agreement is key in not only measuring color, but communicating it–especially across complicated supply chains. Inter-instrument agreement (IIA) measures how similar two or more identical devices (for example two Color Muse) can measure the same color. This is probably the most important parameter in communicating color measured with two devices between different sites. It is like speaking with the same language but with different accents. If the accents are too great, two people cannot communicate. For color measurement, it is generally accepted that humans on average cannot distinguish colors below 1.0 dE2000 (read more about dE2000 here) In my opinion, color measuring devices exceeding 0.5 dE2000 average in real-world IIA across thousands of colors is not useful for any use beyond finding color inspirations. This is because these two devices are really talking about different colors even if they are scanning the same color. Any small decrease in IIA will translate to a massive improvement in color matching because the uncertainty between the two is much tighter. To me, an average IIA of less than 0.2 dE2000 will yield an instrument fleet capable of distinguishing and communicating even the tightly spaced whites (~0.7 dE) for many architectural coatings colors.

2.An instrument’s stability or repeatability over time is an important consideration. The stability of the color measurement system is made up of many factors; how a light source degrades over time, overall mechanical stability, how plastic and organic materials age, and how temperature can change the photon to electron conversion efficiency in the detectors. In my opinion, repeatability of less than 0.1 dE2000 would be suitable for general color matching.

3.For 45/0 optical geometry, circumferential illumination is essential to minimize directional shadowing. Illuminating a surface from just two directions in a 45/0 geometry is simply not enough. This is most apparent in textured surfaces where two directional illumination will read color differently depending which way the instrument was placed on the surface. Note: other optical arrangements such as d/8, d/0, multi-angle may suit specific applications.

4.Full-spectrum illumination allows the eyes to see across all the wavelength of the visible spectrum. If the illumination have large peaks and missing wavelengths, spectral features in those areas of missing illumination wavelengths can yield inaccuracies in the color measurement. LED use in color measurement can be tricky since many LEDs do not have full spectrum illumination with 400-440 nm usually missing in the LED sources. When considering color measurement devices, full-spectrum illumination from 400-700 nm will yield improved measurement for colors in the edge of the measurable color space.

5.Prefer reflectance curve from spectrophotometer instead of Lab color from colorimeters (you can read more about spectrophotometers vs. colorimeters here). One of the key benefits of the reflectance curve is the ability to measure color under different illuminates. For spectrophotometers, look for color reflectance curve output at 10 nm increments. While there may be instruments that measure in 30-40 nm increments, this is not enough from an industry standards standpoint because the larger increment size can lead to inaccuracies when there are sharp spectral features. Most color databases and software use 10 nm increments and conforming to that standard can also save time and money.

As color measurement methods become more advanced and device offerings vary in the consumer market, these are the most telling and reliable ways consumers and color professionals alike can assess device performance.