Light Color

The Technical Memorandum, TM-30-15, the new method published by IES in 2015 and has been proposed to the CIE. This new color evaluation function is expected to provide the angle of technological innovation for light source measuring, furthermore, it can help users analyze the color characteristics of the modern and the traditional solid-state light source, and thus enhance the fairness and accuracy of the measurement.


TM-30-15 uses 99 samples

TM-30-15, which considers 99 real-world objects having a variety of colors – these were carefully chosen for their reflectance properties. (Based on 105,000 objects)

TM-30-15 Measurement Index

TM-30-15 including Color Vector Graphic, Color Fidelity Index (Rf) and Color Gamut Score (Rg)


Color vector graphics use visual description to tell us the changes of hue and saturation. The graph below tells us how various colors are distorted.

The above 3 lights are close to color temperature 3500K. If we use them on plant landscaping, and we expect to bring people a greenery feeling.

Red line: test source (Light A, B, C)

Black line: reference illuminant


For A light on the color Vector Graphic

Red circle on the green gamut is outside black circle; it means green color is over-saturation.

For B light on the color Vector Graphic

Red circle on the green gamut is inside the black circle; it means green color is under-saturation.

For C light on the color Vector Graphic

Red circle on the green gamut is overlap on black circle; it means green color is close to true color.

Users could accord TM-30-15 measure data to determine the effects of saturation and color of the light source.


Fidelity index Rf indicates whether a light source near to natural or not.
Rf = 100 (maximum), colors are most real as the “natural” color.
Rf = 0 (minimum), color shifts occur make seriously color aberration.


Gamut index Rg indicates whether a light source over or under saturation.
Rg = 100, it means no average change in saturation.
Rg > 100, it means the saturation tends to be increased.
Rg < 100, it means the saturation tends to be decreased.
We hope you can get a basic knowledge from above information of TM-30-15. UPRtek also add this function into our product to let customers get the most updated technology. For more information, please check the relatived products below.

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Handbook Series

The Grow Light Handbook

Everything thing you need to know to get started on Indoor Farming, PAR meters, and Grow Lights  – history, industry, vertical farming, PPFD, types of lights, photosynthesis and more!

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About UPRtek

United Power Research and Technology

UPRtek (est. 2010) is a manufacturer of portable, high-precision light measurement instruments; Handheld Spectrometers, PAR meters, Spectroradiometers, Light Calibration Solutions.

UPRtek HQ, R&D and manufacturing are all based out of Taiwan, with Worldwide representation through our certified Global Resellers.

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UPRtek's partner in China, Quelighting Optoelectronics Co., Ltd, and Plant Growth Chamber Manufacturer Ningbo Jiangnan Instrument Factory will attend the 30th International Conference on Arabidopsis Research (ICAR ) which is being held on June 16-21 at Huazhong Agricultural University in Wuhan City, Hubei Province, China.

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