What's CRI, IES TM-30, TLCI & CQS and Why is It Important? Part.1

The colour rendering index (CRI) is a standard in the lighting industry for evaluating the ability of light sources to reproduce true colours, and is easy to calculate and understand by both professionals and consumers. (Click it to know more about CRI)

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However, CRI is limited in its evaluation as it only considers the reproducibility of the light source for a small number of specific colors, while ignoring other important factors. The emergence of these indices compensates for some of the shortcomings of CRI and provides a wider range of indicators for evaluating the colour reproduction ability of light sources.

In various industries, such as textile mills, printing plants, automotive paint shops, hotels, restaurants, bars, museums, galleries, exhibition halls, and healthcare, lighting plays a crucial role in creating a safe, efficient, and engaging environment.

For instance, high color fidelity lighting is essential in industrial settings to enable workers to perform precise tasks and quality inspections accurately. In hospitality environments, bright and highly saturated colors create a pleasing space, making people look their best. In art settings, accent lights with excellent color rendering and high color saturation significantly impact visitor engagement and improve the viewing experience of artworks or exhibits.

In healthcare, identifying subtle differences in color accurately and rapidly can save lives. Medical staff need high-quality light to produce reliable visual information during surgical procedures. The saturated red in the spectrum is best for displaying subtle red hues in the wound area, which are diffused by red tissue and colored in the blood.

Therefore, more color indicators are necessary to provide data support for users in various industries to make informed choices.

TM-30

The TM-30 standard is a method for evaluating the colour quality of light sources published by the Illuminating Engineering Society of North America (IES). It is an internationally recognised set of guidelines for characterising the colour rendering performance of almost any light source (such as LEDs).

This standard provides a more comprehensive assessment of the colour quality of new light sources, particularly for solid-state lighting (SSL).TM-30 is widely regarded as a more accurate and objective indicator for evaluating light colour.

Comparing to Color Rendering Index (CRI) defined by CIE 13.3, TM-30 brings different concepts, and multidimensional metrics are mentioned in the new method. Not only has its evaluation template increased from 8 to 99, but it can also more accurately reflect the colour rendering ability of the light source.

Yujileds® provides the TM-30 tested products and data for evaluating its high color quality LED.

Currently, TM-30 is used in conjunction with CRI, but it will eventually replace the CRI indicator. TM-30 evaluates light source color reproduction using the Fidelity index, Gamut index, and Color Vector Graphic. Unlike CRI's Fidelity Index, TM-30 uses 99 color evaluation samples (CES) instead of just 8.

Rf indicates how similar each standard color appears under the test light source compared to the reference light source (with 100 representing complete similarity and 0 representing significant difference). The TM-30-15 Fidelity index includes 99 colours selected from the real world, divided into 7 groups: Nature, skin colour, textiles, paint, plastics, printing materials, and colour systems.This classification is useful for LED lighting, as testing can be application-specific. For example, if an artist wishes to showcase certain paint colours, they can choose lighting with a high index for the paint colour categories. 

Rg represents the change in saturation of each standard colour compared to the reference light source under the test light source. A value of 100 represents the same saturation, values above 100 indicate that the light source can increase the saturation of the colour, and values below 100 indicate that the saturation of the colour is lower under the test light source.To achieve acceptable color quality when viewing LEDs, the score should be between 80 and 120. A higher score indicates higher saturation or color intensity. If the score is above 100, the color will be stronger than natural colors under sunlight.

Color Vector Graphic isused to measure how certain colors appear together with observed light and whether they appear dull or vivid. Colour vector graphics are an intuitive tool that can display the saturation of colours visually. This chart serves as a supplement to Fidelity and Gamut indices, which are based on averages and cannot determine which colours are saturated.If you have specific requirements for LED lighting, then colour vector graphics are crucial. These graphics, used in conjunction with Rf and Rg values, will help to accurately represent the true colour of the light source.