Summarize
- The CRI value measures the colour rendering of light more broadly than the Ra value
- High CRI value improves the natural colour rendering of lighting
- Ra value does not take into account all colour tones, such as skin tones
- LedStore reports the actual CRI values of its products
- Professionals appreciate high CRI in working environments
There is a difference in colour rendering between CRI and RA values of LEDs. LED lights that produce white light have been accused of producing a bluish or even greyish light, and not without a reason. Regardless of whether the colour temperature of the light is chosen to be, for example, warm 3000 Kelvin white, or neutral 4000 Kelvin white, blue wavelengths have been higher in the past compared to eg. an incandescent lamp due to LED technology. Simply put, red wavelengths have been difficult for the LED to reproduce, accentuating the bluish tones and preventing the correct colours of objects from showing up in the LED light.
The colour rendering index, CRI, of LEDs has improved dramatically, and lights are beginning to produce a more even distribution of wavelengths. For those who want good colour rendering, it is important to choose products with a high CRI, rather than relying solely on Ra. This is because CRI measures half as many wavelengths as Ra. CRI 100 is the maximum value and CRI -100 is the minimum value, where the effect of light makes a particular shade appear weaker than it actually is.
LedStore measures and reports the actual CRI values of all its products.
This article provides a general, concise overview of the impact of colour rendering on LED lighting. This is not intended to be a scientific, absolute fact, and the quality of light is affected by factors other than colour rendering.
CRI, or colour rendering index, indicates the distribution of light wavelengths better than Ra
If you want good colour rendering from your light, be careful with the CRI. It is not the same as the Ra value traditionally used to measure the colour rendering of light. The Ra value measures the rendering of colours using eight different reference colours. CRI takes into account a wider range of wavelengths, including red and other warm colours. The Ra value is calculated by cutting across the wavelength scale, weighting the blue and violet tones, and calculating the weighted average of the R numbers 1-8. The Ra value excludes, among other things, the colour rendition of bright reds, yellows and greens, as well as shades close to skin tone. These are described by R-scores of 9-15. In this latter section, R 9-15, LEDs have traditionally fallen short on the results.
The traditional Ra value is the weighted average of colours 1-8. The CRI is the average of the whole scale from 1 to 15. The CRI of this luminaire is closer to 70, which means that it does not reproduce all colours with high quality.
The following figure shows the exact measurement results for Ra and CRI values.
The figure above shows in more detail the R-values 1-15. The seller claims a Ra figure of 92 for the light, but if you calculate the CRI figure for the light, it is estimated to be less than 80, which is not a high colour rendering value. It is therefore not a high CRI luminaire. Even a ten-unit increase in CRI will significantly improve colour rendering quality. In comparing of cri 80 vs cri 90, the latter is definitely worth choosing.
CRI value is not equal to Ra index
The same LED light can have a good Ra index but a poor CRI, because there are two ways of calculating colour rendering, from R values 1-8 to get the Ra index or from R values 1-15 to get the CRI. Only a high CRI indicates that the luminaire has good colour rendering and reproduces the light spectrum well.
RA vs. CRI or why CRI is better
- The Ra index generally gives less information about the quality of light from a LED than the CRI
- The Ra index does not indicate how well the LED reproduces skin tones
- The Ra index does not indicate how well the yellow, dark blue or red tones are reproduced by the light
- The Ra index can also be wide, but the CRI value is always wide, covering 15 tones.
Less blue, more natural colours
By choosing a LED with a high colour rendering index, the overall look of the room will reflect the natural colours of the space. A high CRI value indicates that the lighting reproduces a wide colour gamut. The closer you get to 100, the more natural the repetition of colours becomes. LedStore’s newer generation of lights with over 90 CRI also feature higher quality LED circuits, which translates into brighter light with less energy consumption.
In the pictures below, the lights have the same LEDs, but the CRI is better in the right-hand light.
When comparing the rendering of colours at different CRI values, there is a clear difference between left CRI 80 and right CRI 97. Only the CRI value has changed in the images.
Watch the video below for more information on this topic, presented in an illustrative way.
High colour rendering is particularly appreciated by professionals and people working with colour
Lamppukauppa Led Store Ltd offers high colour rendering lights for everyone, because in good quality light things look as they should and the light is pleasant to be in.
On our website you can find references such as a hairdressing salons and a relaxation lounge where top quality lights have been used. Here are links to these posts:
High-quality work lighting for the hairdresser’s salon
Sensory-friendly lighting for relaxation lounges
We have published many pictures of objects illuminated with LedStore luminaires in the photo galleries on our website. You can access the gallery of client photos here:
Welcome to the shop!
We are also happy to illustrate the effect of colour rendering in our store, where we have renovated some spaces with different types of lighting, at Koivuhaka, Mesikukantie 16, Vantaa. Current opening hours can be found on our website.
Below is a video of the store:
