The Color Rendering Index (CRI) is an international unified method for defining the color rendering of light sources. It is designed to provide an accurate quantitative evaluation of the degree to which the color of an object under the measured light source is consistent with the color presented under the reference light source. The Commission internationale de l 'eclairage (CIE) puts the color rendering index of sunlight at 100, and the color rendering index of incandescent lamps is very close to that of daylight and is therefore considered an ideal benchmark light source.
CRI is an important factor to measure the ability of a light source to reproduce the color of an object. High CRI value, the stronger the ability of the light source to restore the color of the object, and the easier it is for the human eye to distinguish the color of the object.
CRI is a method of measuring the performance of a light source in color recognition compared to a standard light source (such as daylight). It is a widely accepted metric and the only way to evaluate and report the color rendering of a light source. Color rendering is a qualitative evaluation that measures the degree to which a light source presents the color of an object, that is, how realistic the color reproduction is.
High Light color rendering (CRI≥90) can produce soft light, effectively reduce visual fatigue, make the field of vision clearer and the image more three-dimensional; bringing users a high color rendering and lightweight outdoor lighting experience. High color rendering have good color reproduction effects, and the colors we see are closer to natural primary colors (colors under sunlight); low color rendering have poor color reproduction, so the color deviations we see larger.
How to choose color rendering/color rendering index when purchasing lighting equipment?
When choosing color rendering, two principles are usually followed, namely the principle of faithful color rendering and the principle of effective color rendering.
（1）Faithful color rendering principle
The principle of faithful color rendering means that in order to accurately represent the original color of an object, a light source with a higher color rendering index needs to be selected. In this case, selection can be made based on the Ra value. The larger the Ra value, the higher the degree of restoration of the original color of the object. Different applications have different requirements for faithful color rendering of light sources.
According to the different applicable venues, the International Commission on Illumination (CIE) divides the color rendering index into five categories:
|
Color rendering category |
Ra value |
color rendering |
Scope of use/faithful color rendering requirements |
|
1A |
90-100 |
excellent |
Where accurate color contrast is required |
|
1B |
80-89 |
good |
Where medium color rendering is required |
|
2 |
60-79 |
ordinary |
Where medium color rendering is required |
|
3 |
40-59 |
relatively poor |
Places with relatively low color rendering requirements |
|
4 |
20-39 |
poor |
Places with no specific requirements for color rendering |
（2）Effect color principle
The principle of effect color rendering is that in specific scenes such as meat product display cabinets, in order to highlight specific colors and display beautiful life, a specific color rendering index needs to be selected. On the basis of ensuring that the Ra value meets the requirements, the corresponding special color rendering index is increased according to the color of the illuminated object.
In the meat display area of supermarkets and various stores, the color rendering index R9 of the lighting source is particularly critical, because the meat color is usually biased to red, and a higher R9 can make the meat present a more fresh and delicious visual effect.
For scenes such as performance stages and studios that require accurate reproduction of skin tones, the color rendering index R15 of the light source must meet a high standard.
Expand Knowledge
The theoretical color rendering index of incandescent lamps is 100. However, in life, there are many types of incandescent lamps with different uses. Therefore, their Ra values are not uniform. It can only be said to be close to 100, which is considered to be the light source with the best color rendering performance. . However, this type of light source has low light efficiency and lacks the advantages of energy saving and environmental protection. In contrast, although LED lights are slightly inferior to incandescent lights in terms of color rendering performance, they have become a more popular light source due to their energy-saving and environmentally friendly properties.
In addition, if the human body is exposed to a lighting environment with poor color rendering performance for a long time, the sensitivity of the cone cells of the human eye will gradually decrease, and the brain may involuntarily concentrate more when identifying things, which can easily lead to eye fatigue and even myopia.
The color rendering index of classroom lighting sources should not be lower than 80. Too low color index of classroom lighting will affect students' eyes' accurate recognition of the color of objects, causing objects to be unable to present their original true colors. If this situation continues for a long time, it will lead to the decline and decline of color discrimination ability, which will in turn induce serious vision problems and eye diseases in students such as color blindness and color weakness.
The color rendering index Ra>90 is used for office lighting, its appearance satisfaction can reduce the illumination of more than 25% compared with the lighting facilities with a low color rendering index lamp (Ra<60). The color rendering index and illumination of the light source jointly determine the visual clarity of the environment, there is a balanced relationship between illumination and color rendering index.
Post time: Apr-03-2024
