How often have you seen a client bring an item of clothing to a natural source of light to discern its true colour? Too often, no doubt. In the retail sales market, colour plays a critical role; it can make or break a sale. Where there’s a doubt, there’s no sale. Avoid discussions and problems. Select the appropriate lighting system for your shop. Make sure to examine your lighting CRI (colour rendering index).

What is the CRI?

The Colour Rendering Index measures the quality of the light source that affects the appearance of objects in terms of colour. Following colour temperature, the CRI ranks second as variable used to define a source of light, and thus to measure its quality. Comparing the CRI of two distinct light sources that have differing colour temperatures makes no sense.

How do we measure the CRI?

The International Commission on Illumination (CIE) sets CRI standards and defines it by comparing the source light to be tested to a reference source that records the identical colour temperature. A colour rendering test is done on 15 selected colours. An average is then calculated based on the results to determine the CRI. This colour rendering index results in an average colour rendering for each single colour. The colour red (R9) is the most difficult to revive and is often weak. This is why we tend to examine the rendering of the red instead of taking the average into account.

Color Rendering Index Chart infographic


The Ideal CRI for Each Type of Lamp

The conventional R100 indicator for colour rendering is the “ideal” white light, i.e., light of day or an incandescent lamp. Conversely, a null R0 colour output would be the light dispersed by a monochromatic lamp such as a sodium-based vapour bulb that allows no colour distinction whatsoever.

Color Rendering Index for lamps infographic

Colour Rendering Index Evaluation infographic


What is the Ideal CRI?

This is a difficult question. To begin we must examine the space that the lamp will illuminate as well as the objects and areas that the light source will draw attention to. When you need to highlight the colours of your store’s clothing displays, make sure to get to know the colour rendering of each item instead of taking the CRI into account. This way, your colours will be more precise and accurate.
For example, if you need to light up your meat counter, colour rendering of the red is essential if don’t want your meat to have a brownish tint.

The optimal CRI is the one that faithfully reproduces the colour of articles and products in your store.

For more details concerning the lighting product best suited to your needs, contact our lighting specialists.

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