What does Wikipedia have to say about the CRI: “The color rendering index (CRI) (sometimes called color rendition index), is a quantitative measure of the ability of a light source to reproduce the colors of various objects faithfully in comparison with an ideal or natural light source. Light sources with a high CRI are desirable in color-critical applications such as photography and cinematography. It is defined by the International Commission on Illumination as follows: ‘Color rendering: Effect of an illuminant on the color appearance of objects by conscious or subconscious comparison with their color appearance under a reference illuminant’.”

As this sounds a wee bit complicated, we’ve prepared an article which (hopefully) explains a bit mor simple what the CRI is and does. First of all, please note that the CRI is different from the light colour or colour temperature of the lamp. Even so-called “daylight” bulbs may have a comparatively low CRI (as per full-spectrum standards anything below 90 is seriously low) and it is the CRI rather than the colour temperature (measured in “K” for “Kelvin” by the way) which makes the real difference when it comes to the light spectrum and ultimately how good you’ll see and be able to do visual tasks under such lighting.

Researchers in Sweden found out that with the CRI being around or above 96 Ra, it is quite possible that we see up to 30% better when compared to lower quality light sources. So what light sources are those which are preferrable for a good CRI which are those who are not:

I light source with a CRI = 100 Ra would be perfect and balanced in terms of colour reproduction, shading, contrast etc. – therefore the lesser the difference from 100 Ra, the better will colours be reproduced under such light. The lower the Ra-value, the worse colours will reproduced and the more difficult it is to see and work under such light.

A last but important word on the note of colour reproduction:

When comparing different light sources, it is only recommendable to compare them in the same colour temperature. It makes therefore not much sense to compare an incandescent 2700K bulb with a 6500K daylight energy saving lamp. For a proper comparison – either the incandescent lamp should be also rated at 6500K colour temperature or the energy saving lamp should be in the 2700K range. Then – and then only – true colour reproduction comparison can take place.

We hope this helps to clear up some confusion around the terms colour reproduction and colour temperature. Thanks for reading

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Instructions:

1) Name the following colours aloud from up to down. Say aloud, as if there is nobody else in your room. So start from “red”:

2) Now do the same for the following colours, but try a little faster:

Very good. However, did you really name the colours? Why did you say that the upper colour is red, although it is white, as you can see here once more:

Isn’t that surprisingly difficult? A person, who cannot read, will find this test most likely much easier – of course we just guessed that you said “red”, because 99.5 % of all people say so.

BTW: It is also difficult to read in yellowish, eye tireing and insufficient bad colour rendered light. Therefore we suggest that you try clean, full spectrum daylight lamps, like Viva-Lite, in your office and at home. We believe that you will improve your reading speed – not to talk about seeing true colours!

There is a huge difference between different lamps.

Thanks to your Viva-Lite partner in Finland for providing the test!

Related posts:

1. The Colour Rendering Index (CRI)

Dave – one of our kind customers in Australia has sent us the following pictures of an energy saving lamp with the Viva-Lite Spectrum and the Sunlight as a comparison:

Both photos were taken through so-called “Spectral-Glasses” which you can get in many stores and on the internet. Or buy them directly in the Viva-Lite International Online-Store and compare for yourself…

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1. The Colour Rendering Index (CRI)
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