Color rendering index: the importance of CRI

It often happens to read among the technical specifications of LED luminaires, such as lamps, LED modules for signs or LED strips, data relating to the color rendering index, better known as CRI.
In this article we will explain what this data refers to and what are the advantages related to a higher CRI in different areas of application.

What is the CRI?

The CRI, or color rendering index, is a scale ranging from 0 to 100 that indicates the ability of a light source to truly represent the colors of an object illuminated by it. The higher its value (tending to 100), the more faithful the color rendering of the objects it illuminates will be. So what does the color rendering index mean? The color rendering index indicates the ability of a lamp to faithfully show the colors of the objects it illuminates. The CRI is determined by the light spectrum emitted by the device in question but should not be confused with the temperature of the light (or color of the light). In fact, the same color, or temperature, of light can be formed by many, few, very few or even only a couple of electromagnetic waves, which will result in a huge difference in color rendering. A wider light spectrum results in a higher CRI. In practice we can consider the natural light of the sun as a CRI 100, since it includes the light spectrum in its entirety, all artificial devices, whether they are LED modules, incandescent lamps or neon tubes, will have a variable value depending on their characteristics. constructive and a CRI inevitably lower than 100

CRI Categories

 The CRI (also called RA or IRC), attributes a qualitative value referred to the color rendering to all the devices that emit light. The latter, which can be LED lamps, traditional bulbs, neon or LED modules for signs, are commonly divided into 5 categories:

• CRI 90 and more - Very high yield (1A)
  The maximum yield possible, these devices are intended for applications where chromatic fidelity is essential such as museums, operating theaters and shops, or where the correct and faithful representation of colors is an essential requirement (as in the case of illuminated signs for large brands).

• CRI > 80 - High yield (1B)
  Used for homes, schools, offices and production areas where excellent light quality is required.

• CRI > 60 -  Second class
  Used for stairs, corridors, transit areas, public services and changing rooms.

• CRI > 40 - Third class
  Used for warehouses, industrial areas, greenhouses and sheds.

• CRI > 20 - Fourth class
  Construction sites, temporary places, unloading areas, emergency or precarious situations.
  

What does CRI 90 mean?

If a lamp or LED module has CRI 90, it means that it will have a high capacity (color rendering) to correctly represent the colors of the objects it illuminates. Often the words CRI> 90 or CRI 90 + are found, which means that the CRI is certified as higher than 90. It must be borne in mind that the human eye is not able to perceive color variations higher than CRI 90, we can therefore say that a CRI 90+ or ​​CRI> 90 rating represents the maximum appreciable color rendering without the use of tools.

What does CRI 80 mean?

As we have seen from the description of the CRI category, CRI 80 means a good color rendering index, not comparable to that of CRI 90, but suitable for general domestic lighting or work environments. In case of need to have an optimal representation of colors (such as in the case of food lighting or in the creation of a luminous sign for a particularly demanding brand), it is recommended to use devices with CRI> 90.

CRI > 90 LED Modules

As seen above, one of the areas of application that increasingly requires a chromatic index as faithful as possible, is that of LED luminous signs. In this context, in fact, the sign manufacturer not only carries out artisanal and artistic work, but also embodies and reproduces the values ​​and distinctive features of the brand that it must represent. It therefore becomes essential to have absolute chromatic consistency with respect to the colors of the brand that is being promoted.

In this regard, the first LED modules for signs with CRI higher than 90 are being developed. The new 24v miniMax LED modules by Current are an excellent example, already used by many Italian teachers for the creation of boxed letters and backlit signs for high-profile brands, particularly attentive to respect for corporate colors.