The CRI (Colour Rendering Index) is a measure of the colour rendering quality of a light source. It indicates how well a light source reproduces the colours of objects in comparison to a reference light source, e.g. a daylight spectrum.
The colour rendering index is measured on a scale from 0 to 100. A value of 100 means that the light source reproduces the colours of objects perfectly. A value of 0 means that the light source does not reproduce the colours of the objects at all.
LED lamps usually have a CRI of 80 to 95, which means that they reproduce the colours of objects well. However, LED lamps with a colour rendering index of 100 have recently been introduced by manufacturers such as YUJILEDS and are particularly suitable for use in areas where the quality of colour rendering is important, e.g. in photo studios or museums.
In the printing industry, D50 standard light is the common standard light in Europe. Whether you need D50 standardised light depends on your requirements. If the colours of objects and prints need to be reproduced very accurately, D50 standard light is the best choice.
However, if the requirements for colour rendering quality are not so high, an LED with a high CRI can simply be used. LED lamps with a high colour rendering index are generally cheaper than D50 lamps and easier to find.
At Proof GmbH, we have standard light booths from Just with D50 standard light, but we often only use an LED with 500 Kelvin and the highest possible CRI of 90+ on the winders. Nevertheless, significant colour differences and metamerism effects often occur here when proofs are only viewed on the cutting table. We therefore always use the standard light booths for a comprehensive colour assessment.
Unfortunately, no retrofit solutions are currently available for simply replacing ‘old’ D50 standard light neon tubes with LED tubes, for example. As neon tubes will be banned from 2024, completely new LED units must currently be purchased and installed from Just, for example, when replacing old D50 standard light neon tubes. However, at several thousand euros, the replacement is currently still quite expensive.
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