What is CRI - Color Rendering Index?

The color rendering property of a light source is very important. The coefficient of this parameter allows you to determine the ability of a light source to recognize colors. On a scale of 1-100, one describes monochromatic light, and one hundred describes the natural sun. A newer color rendering index RA is CRI, which measures sixteen basic colors. The RA coefficient determines the general color rendering index, while CRI is a numerical assessment of the ability of a light source to correctly reproduce the color of various objects compared to natural or daylight. What exactly is the CRI coefficient? What is the meaning of CRI LED?

What is the color rendering index?

Few people wonder why in daylight, emitted by the sun, the color of a car looks different than under artificial light, emitted by street lamps. Devices that illuminate streets and everything surrounding them and within the range of light after dark are characterized by a relatively low CRI, which makes the colors seem changed.

It must be admitted that most objects on earth do not emit their own light. However, they can be seen because they reflect the light that falls on them. The ability to receive sunlight changes in the eyes. In such light, all shades can be seen, but the current way of life of many people means that they spend more time indoors. They spend less and less time in direct sunlight and definitely rely more on artificial light, emitted by lamps, among others.

As a result, great attention should be paid to bright indoor lighting, because it is the only way to obtain a good representation of the colors that are seen. Only when there is a difference in luminance or colors between the viewed object and the background is visual perception possible. Finally, various types of light sources are used for lighting. Energy-saving solutions such as LEDs are gaining popularity year by year.

The perception of a given color by humans is based on the interaction of vision with the brain. Color and brightness receptors, which are located in the retina of the eye, enable the perception of light. In the process of vision, photon energy is responsible for controlling color, which is defined as saturation and hue. Importantly, the three color characteristics that determine a person's ability to perceive color, i.e. saturation, hue and brightness, are mostly determined by the parameters of the light source used.

What is the RA color rendering index and CRI?

The color rendering index of a lamp is defined by its value on the RA scale. For example, a light bulb with a CRI of 100 means that it has the highest possible CRI. In turn, a CRI of 0 means that it has this parameter. The color rendering index is given on a scale of 1-100. It describes the ability of light to recognize colors. On a scale of 1, it is monochromatic light, while on a scale of 100 it presents natural light. Therefore, in this case, the scales can be defined as a measure of light quality.

The CRI color rendering index, from English color rendering index, is an indicator that determines how well a given color is reproduced, when the color temperature indicates the color of the emitted light. An example of differences in color perception can be two rooms, e.g. a warm café with a low color temperature and an aesthetic medicine clinic where white lamps with a high color temperature are used.

Both of these rooms affect how a person perceives colors and they are often incorrectly defined. This also means that if you want to correctly assess the CRI index of two bulbs, they should have the same color temperature. Importantly, the color rendering index is just one of many features that enter into the specifics of a given light source.

What is the significance of the LED CRI index?

CRI, or the color rendering index, characterizes a light source. It is presented on a scale from 1 to 100 and determines the way in which colors are presented under the influence of light falling on it. The higher the index, the better the colors are reproduced, and objects seem more natural. Importantly, CRI and Ra are abbreviations that can be used interchangeably. If Ra is 100, it means that the colors are optimally reproduced as if they were in the sun. Colors that have a low CRI can be very distorted. Sodium vapor lamps, which until recently were widely used as street lighting, are a perfect example of such an index.

However, they are increasingly being replaced by modern and energy-saving LED lamps, which are characterized by a high CRI. Importantly, this coefficient is calculated on the basis of fourteen specific test color samples, although manufacturers usually use eight. Test light sources define color patterns. The RA index is calculated by comparing the light reflected from the test colors with the light reflected by the reference light.

What is the significance of the RA index for health and well-being?

If the index is lower than 80 CRI, a person may feel worse and their eyes will tire more quickly in rooms with such lighting. The reason is that the colors will not be natural. All shades will seem darker, and such perception has a negative impact on the human psyche.

For most people, the optimal solution is a high color rendering index and a pleasant light color temperature. The natural and at the same time the highest RA values ​​can be found in workplaces. Then a person feels better, their eyes are less tired. Objects lit by lamps with poor color rendering may look worse than those lit by the same color but with a higher RA.

What CRI should you choose for your home?

To sum up the entire article, you can come to the conclusion that the best CRI will be one above 80. Bulbs with such a color rendering index should be used wherever it is necessary to ensure that the most natural colors of illuminated objects are maintained. Offices, warehouses, art galleries, or home walls with photos are places for which it is worth choosing lighting with the highest possible CRI. A slightly lower index can be used where perfect color rendering is not necessary.