Color rendering index plays a vital role in the world of lighting. This key metric tells you how light reflects the true color of an object, helping users understand the quality and effectiveness of a light source.
Understanding CRI can help you make the right lighting choices in your setup. This blog explains all the details you need to know about CRI.
Basic definition of CRI
CRI, or Color Rendering Index, is a measure of the ability of a lighting device to reproduce the true colors of an object compared to natural sunlight. The CRI value range is 0 to 100, and the higher the value, the stronger the light source's ability to reproduce colors. If the range shows a value of 100, it means that the light has perfect color rendering, the same as natural light.
How to calculate CRI?
CIE first introduced the concept of CRI to the world in 1965. The calculation of CRI is based on the standards set by the International Commission on Illumination (CIE). Specifically, by shining a light source onto a set of standard color samples, the degree of color deviation is measured. Developers use the difference between the test light and the reference eight standard color samples. They calculate the difference in color appearance to finally derive the CRI value. The smaller the difference, the higher the CRI.
How to measure CRI?
CRI is usually calculated using the CIE-1974 test color analysis. It contains 14 color samples. The first 8 color samples are called TCS. TCS is used to measure basic CRI. It contains samples of soft colors such as medium blue, yellow-green, grayish yellow, and light red with gray. The remaining 6 of the 14 color samples are used to measure specific color analysis.
You can measure the color rendering index by following these simple steps:
- Select a reference light source: Make sure the test light and reference light have the same color temperature.
- Illuminate a color sample: Check the TCS illumination of the test light and reference light.
- Compare color rendering: Calculate the color difference by matching the samples of the reference light and the test light.
- Calculate CRI: Measure the difference and give a value of the CRI score (0-100) of the test light.
Why is CRI important to luminaire manufacturers?
Luminaire manufacturers need to provide light sources with a high color rendering index to ensure that users can get accurate color perception.
Here are the reasons that explain the importance of CRI:
- Accurate color perception: Places such as medical institutions, art spaces, photography studios, and retail stores require high CRI lamps. This helps them see the true colors of objects.
- Enhanced visual comfort: High CRI lamps provide a natural lighting experience, thereby reducing eye fatigue.
- Improved aesthetics: Places with exquisite architectural designs require high CRI lamps to enhance the overall aesthetics of these places.
Application of CRI in Different Scenarios
The required CRI rating varies from application to application. This means that different places require different ranges of CRI to improve their lighting.
Residential Lighting: Lighting used in residential areas must have a CRI of 80 or above. This rating ensures that you see the true tones of the decorations, furniture, and settings.
Retail Lighting: Retail stores must use lamps with a CRI of 90 or above. The true look and vibrant colors of products attract more customers and increase your sales.
Art Galleries and Museums: Such places require high CRI lamps (with a rating of 95 or above) to display the accurate colors and appearance of artworks.
Photography and Videography: In photography studios, lights should have high CRI to capture the accurate colors of objects and people.
Medical and Dental Facilities: Doctors need bright light with high CRI so that they can diagnose the underlying causes of their patients and perform effective treatments.
Industrial and Manufacturing: These places also require high CRI lamps to detect errors and defects in products early.
Comparison of CRI and other light source performance indicators
1. CRI and color temperature (CCT)
Both color temperature and CRI are important factors that affect the performance of light sources, but they measure different properties. Color temperature (CCT, Correlated Color Temperature) describes the hue of the light source, such as warm light (2700K) or cool light (5000K), while CRI focuses on the accuracy of the light source's color reproduction. A light source can have both high color temperature and high color rendering index, or it may have poor color rendering at high color temperature.
2. CRI and luminous efficiency
Luminous efficiency refers to the energy efficiency of the light source, usually measured in lumens per watt (lm/W). High-efficiency light sources do not necessarily mean high CRI, and some energy-saving lamps improve luminous efficiency at the expense of color rendering. Therefore, while pursuing energy saving, the importance of CRI cannot be ignored.
3. CRI and chromaticity deviation (Duv)
Duv is a parameter used to measure the chromaticity deviation of a light source, which indicates the difference between the color of the light source and the ideal white light. Although CRI can measure the ability of color reproduction, Duv can reflect the overall color tendency of the light source. Especially in high-precision applications, Duv and CRI need to be considered together.
Comparison of CRI values of common light sources
1. LED lamps
LED lamps are one of the most commonly used light sources in modern times, and their CRI values are usually between 80-90. High-quality LED lamps can achieve a CRI of more than 90, which is suitable for high-precision lighting scenes.
2. Fluorescent lamps
The CRI of traditional fluorescent lamps is usually between 70-85. Although the energy-saving effect is good, its color rendering performance is relatively low, and it is not suitable for occasions with high color reproduction requirements.
3. Incandescent lamps
The CRI value of incandescent lamps is close to 100, which can almost perfectly restore the true color of objects. However, incandescent lamps have low energy efficiency and are gradually being eliminated.
Limitations of CRI
CRI is considered a useful measurement tool, but it also has some limitations.
- Limited sample colors: The results of CRI are essentially based on only 8 color samples. This does not represent the wide range of colors in the real world.
- Equal weighting: All 8 color samples of CRI have the same weighting. This means that it cannot represent the importance of certain colors in certain applications.
- Color temperature dependence: The results of CRI may change with changes in color temperature. This means that applications with different color temperatures cannot display accurate CRI.
- Lack of saturation information: Some applications require saturation, and CRI does not have the ability to measure color saturation.
How to choose the right CRI for lighting?
Choose according to the application scenario
Different scenarios have different requirements for CRI. When choosing lamps, it is crucial to consider the specific needs of the application scenario. Generally speaking:
Home lighting: CRI ≥ 80
Commercial display: CRI ≥ 90
Professional workplaces (such as medical, photography): CRI ≥ 95
In order to choose the right light, you need to follow some factors to achieve better color rendering:
Color temperature: Make sure the color temperature of the selected light source is suitable for your environment. For example, warm light is used for homes and bright white light is used for commercial areas.
Lighting technology: Please choose the right technology appropriately, as each lighting fixture has different CRI levels.
Manufacturer specifications: Always check whether the lamp you choose is verified and tested for CRI accuracy.
Future Trends in Color Rendering
The color rendering industry has been evolving over time. Ongoing research is aimed at improving its measurement systems.
- Advanced metrics: Units such as CQS and TM-30 provide more detailed and accurate color rendering results. Therefore, they are better known than CRI.
- Human-centric lighting: Developers focus on creating human-centric lighting. They have better color rendering capabilities and are harmless to human health.
- Smart lighting solutions: Smart lights give users full control over their CRI and color temperature. This enables them to customize the light to their needs.
- Sustainable lighting: Today's generation is more focused on using sustainable equipment. New eco-friendly lamps offer better color rendering.
Conclusion
One needs to understand CRI before making the right lighting choices. This simply means the way you see an object in real light; these lights will show you how the object will look the same way it would under its own lighting. Some setups require high CRI lights, while others require low CRI lights. Therefore, you must know where to place the lights and why. This way, you can make the right decision when choosing the right CRI.
At XINSANXING, we offer high-quality lamps that are CRI tested. For more information, please visit our website or contact us via email.
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Post time: Oct-16-2024