TM-30-15 Explained by Megaman

A key advancement in lighting design has been the recent introduction of TM-30-15 as a colour measurement system. This seeks to displace Colour Rendering Index as the current industry standard.

When using the traditional CRI system, the only way a designer can be sure they get the colour quality they want, is by obtaining multiple manufactures’ lamps and testing them in situ. This is because product data sheets cannot guarantee a high colour rendering accuracy because the current CRI system allows for too many inaccuracies.

The CRI system was developed many years ago and uses out-dated formulae and tools by today’s standards. Even before the solid-state lighting revolution, the industry faced issues when trying to compare the colour of different light sources - and the introduction of LEDs has only exacerbated this.

CRI, known as Ra, tends to be inaccurate because itonly uses fidelity (fidelity index – closeness to a reference) to measure light, which is then taken from a maximum of 14 Colour Evaluation Samples (CES). However this index averages only 8 of the 14 colours, which is why many Ra values can be the same for different lighting products.

TM-30-15 on the other hand goes far beyond traditional CRI. This benchmarking system comprises three main components

  • Rf – a fidelity index that is similar to the commonly used CRI
  • Rg – a gamut index that provides information about saturation
  • Colour vector graphic – a graphical representation of hue and saturation relative to a reference source

TM-30-15 uses 99 Colour Evaluation Samples (compared to CRI’s 14) to measure colour fidelity, which uses better colour space, spectral uniformity and covers a broader range of colours. Furthermore, it is a significant improvement that TM-30-15 includes a saturation index (Rg) and new research shows that saturation has a significant affect on our perception of colour rendition and light levels.

TM-30-15 provides a broader and more detailed understanding of colour rendering between different light sources. This represents a more comprehensive way to compare light sources like for like, but also allows manufactures the ideal opportunity to embrace a form of ‘best practice’ when it comes to light measurement.

Ultimately, the introduction of TM-30-15 is helping to create a stronger, credible dialogue between manufactures and designers to ensure lighting specifications are fit for purpose and perform as expected.