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Understanding the Color Rendering Index with LEDs

Time: 2020-04-16

When it comes to the quality of different light sources, the color rendering index (CRI) is an indicator of measurement, and it is necessary to pay attention to CRI when selecting and using light sources. 


Then we will introduce briefly to help you better understand the concept of color rendering.


Color


What is color? Actually, no object itself has color. 

Even the most colorful objects will lose the color if in a completely dark environment. 


Therefore, if an object is dependent upon light for color, color must be a property of light. The mixing of light of different wavelengths usually causes different sensations of color.


For example, when the optical radiation entering the eye-brain system is dominated by longer wavelengths (above 620 nm), red color appears.


* When most of the optical radiation is at an middle  wavelength (around 530 nm), it will appear green.

* When the optical radiation is controlled by a shorter wavelength (about 450 nm), a blue color will appear.

* Mixtures of long and medium wavelengths may appear yellow, and mixtures of short and long wavelengths may appear magenta.


Contrary to observing the experience of viewing objects reflecting and scattering incident light, this helps to distinguish the color experience that occurs when a person directly looks at the light source.



Color Rendering Index


Color Rendering Index, also called as CRI, is a measurement of the ability of color renditions.  It is rated on a scale from 1-100. The lower the CRI rating, the less accurate colors will be reproduced. 


For nomal lighting projects, the outdoor CRI range is RA70 to RA80, while the indoor CRI is RA85 to RA90.But for special places, such as showrooms, printing workshops, or any places that require high color renditions, the CRI index can reach RA95 to RA98 or higher.


Sometimes the lights wil tell lies. The color of the objects in the outdoors is different from indoors. That's because lights have different capabilities in color renditions.



Comparison


In LED Lamps, CRI is associated with the phosphor with which the LEDs are made.  To obtain a higher level of CRI, you need higher quality and higher prices, so few manufacturers use values above 90 to maintain Lower price and competitiveness.


If you take a look at cheap LEDs, you will find a big difference. There are many areas in the color spectrum that do not render the light correctly. This is very likely to cause strange tones in skin tones or other color casts in the image, which is unexpected, undesirable and uncontrollable.


The maximum CRI that can be achieved in LED lamps is CRI 98, which is applied in museums, art galleries, clothing stores, Supermarkets cosmetics, and other applications that need high-quality colors.



LED light sources


Who has the best lighting color performance? sunlight, which is defined as CRI100.


Natural daylight contains all colors in the visible spectrum, plus the power or energy level of each color of light is almost uniform throughout the spectrum.


In general, any light source with a CRI rating of 90 or higher will faithfully display color. Most high-quality tungsten sources will have a CRI rating of 90 or higher (usually over 95). Sunshine will be the best of all CRI levels.


In addition to daylight, how to achieve the best lighting color performance? The answer is to have a light source with a complete lighting spectrum and continuous lighting.


To achieve the goal, we have made LED light source at any other light spectrum what ever visible or invisible.



 

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