How to understand the Chromatic Performance Index?

In the case of lighting with LEDs there is a need to ensure that this is as close to natural lighting.

For purposes of evaluating the color of objects, the standard practice is to compare colors under natural (solar) light or use a fluorescent lamp simulator (to match the natural sunlight spectrum). In the case of lighting with LEDs there is a need to ensure that this is as close to natural lighting.

The perception of colors is different due to the color performance properties of the lamps. This performance is called the color performance index or CRI, which is a value used to measure the ability of a light source to yield known colors of objects or materials. For example, the lighting that produces a color similar to that of natural light is said to have a good (high) color performance and can be classified as "natural white", "warm white" or "cold white", and each reproduce the color of an object differently.

The CRI indicates how 15 colors tested look under standard illuminance.

When comparing the illumination with the standard reference light source, a CRI index of 100 is the best; In these cases, Ra is the average of the color performance indices for color tests R1 to R8, which are the typical colors of a general environment.

R9-R15 instead are "special" color performance indices. These are relatively high chroma in red, yellow, green and blue. R9 evaluates the reproduction of red and is important for medical use.

The higher the CRI score, the better the color rendering ability. The highest available value for each CRI is 100 and the lowest possible value is a negative value for certain light sources, such as low pressure sodium lighting. In this way it is understood that the CRI describes the ability of a lamp to render a "true" color of an object as seen in natural sunlight.

Why is the CRI important?

Light sources with a high CRI are important in hospitals and health care centers, photography and videography, because it is essential to see the color correctly. Medical professionals need to see the "true" colors in order to diagnose accurately. The photos and videos will appear more real when the "true" colors are reproduced. In addition, homes and workplaces offer benefits for safety and well-being.

CRI Illuminance Meters

A photometer is an instrument to measure light in illuminance (lux), color temperature (K), chromaticity (XY), color performance index (CRI) and many other technical parameters. But, good CRI meters must have a spectral sensor with an adjustment function that allows the CRI meter to match the response of the human eye as specified by the International Commission of Eclairage (CIE), the international light authority, lighting, color and color spaces.