CRI (Colour Rendering Index)
At Normo, some products display information about their CRI.
What does it mean? And how important is this when choosing a light fixture?
The following is an explanation of this concept in order to better understand this characteristic of light.
What is it?
CRI, or colour rendering index, is a parameter that conveys information about the ability of a light source to faithfully reproduce the colours of a given object compared to a natural light source, which is the Sun.
It is measured on a scale of 0 to 100, and most lamps in the Normo online store have an index of around 80 and 90. This means that the light source of these lamps reproduces around 80% or 90% of the colour spectrum visible in sunlight. The lower the CRI, the more indistinguishable the colours illuminated by this light source become.
When should it be considered?
CRI should be taken into consideration in professional applications (such as art galleries or museums), in the retail sector (in order to meet customer expectations regarding products displayed in store - for example, in a clothing store) or even in offices or work areas where the activity to be carried out has colour as an important or critical factor (printing companies, design studios or workshops but also in a production line, where small variations in colour can be of use, for example, in quality control processes).
How is it calculated?
CRI is determined by comparing the light source with a reference source with the same CCT (Correlated Colour Temperature, since the colour temperature of sunlight varies throughout the day).
The calculation is performed using up to 15 color patterns, which are compared with the colour that is reproduced when each pattern is illuminated by the light source under test. Each pattern is assigned a percentage from 0 to 100 that indicates how much of the light spectrum of that colour is reproduced. The average of these 15 colour patterns results in the final CRI value.
This means that the colour temperature parameter that a given light source may have does not influence its CRI. In other words, a lamp with a very cold light (5000K) does not necessarily have a worse colour reproduction than another lamp with a neutral colour temperature (3000K).
CRI: an indicator of the quality of the light source
For all these reasons, CRI is a crucial criterion in specialized applications and, as such, higher CRI values are typically found in more technical solutions.
Normo has ranges such as the Apallis or iO projectors, which offer high lighting and colour reproduction performance, making them ideal for use in professional contexts.
If you need any help or advice, the Normo team can help you identify luminaires with a high CRI or help with other issues that may arise in your lighting project.
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Last updated: 12/03/2025