For the past years, the LED technology has made a huge progress in the development, and LED lightings are getting more and more popular. However, the past standards has limited ability to measure the LED light source, and other factor must be taken into account to determine a good luminous environment. That factor is called Gamut Area Index (GAI).

Gamut Area Index (GAI) is considered the least useful color metric by surveyed NLPIP members, it is more commonly used in Japan and North America, Asia has also started to pay attention to this index in recent years. In principle, GAI is usually calculated from the area of the polygon defined by the chromaticity of the eight color swatches used in CRI definition for a light source (R1~ R8), the same reference samples used to calculate color rendering index (CRI) in CIE 1976 color space when illuminated by a given light source.

GAI01
The standard of each Gamut Area range on CIE 1976.

The area of the polygon created by this plot is that source’s GAI, so the larger the area, the higher the GAI. High GAI is characteristic of a source with good color discrimination and saturation of colors, or vividness. GAI can be over 100, but this usually means colors appear oversaturated. Generally, architects, lighting specialists, industrial designers, and theatrical lighting designers recommend choosing a source with high CRI (85 or greater) and a high GAI (80-100).

GAI02
The calculations of Gamut Area, the blue area means standard reference, and the red area means the measured value.

Through the creation of the cutting-age SMART spectrometer “Lighting Passport” and the professional “Spectrum Genius Mobile (SGM)” or “Spectrum Genius Essence (SGE)”, your smart device will provide the complete light source measurement information anytime, anywhere, and Asensetek also continue to update the latest international parameters, allowing users to go in the forefront of the industry.

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SGM measurement results page

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Gamut Area Index (GAI) introduction
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