When it comes to selecting LED lights, few factors are as crucial as light color. With a multitude of options available, understanding how light is perceived becomes essential. Before diving into the spectrum of light color choices, it's important to grasp the mechanics of vision. This foundational knowledge sets the stage for appreciating the significance and distinctiveness of different light colors. Depending on the intended application, certain color temperatures may prove more fitting than others.


How is Light Seen?

Colors are different wavelengths of light, expressed on the wavelength diagram below. They are just the visible spectrum of a wavelength chart, measured in NanoMeters (nm). Light, as it is perceived, is composed of a spectrum of electromagnetic radiation with different wavelengths. “As the full spectrum of visible light travels through a prism, the wavelengths separate into the colors of the rainbow because each color is a different wavelength. Violet has the shortest wavelength, at around 380 nanometers, and red has the longest wavelength, at around 700 nanometers” (Science Mission Directorate, 2016).


Wavelength spectrum of light measured in NanoMeters

This is the wavelength spectrum of light measured in NanoMeters


How is White Light Measured? 

If the full spectrum of light is visible, it is seen as white light. White light can be interpreted or determined by comparing it to the light visible from different temperatures of molten iron. This reference gives a temperature that can be used to refer to a specific type of lighting. For example, warm white is comparable to molten iron at 3000K (Kelvin, an actual measurement of temperature)!  


Temperature diagram of white light

This is a diagram showing the temperature of white light.


Soft white (2700K) produces a candlelight ambiance that is often used to create a homey and restful atmosphere. This color temperature is mostly used in bedrooms.
Warm white (3000K) produces a warm, yellowish light that is often used to create a cozy and inviting environment. This is the most popular color temperature; it is commonly used in homes.
Cool/Neutral White (4000K-4300K) produces a neutral light that is often used in commercial settings or workspaces where a bright and clear light is needed.
Day White (6000K+) is the closest color to what the sun emits at mid-day and is often used for outdoor lighting or areas where color accuracy is important. 


How is Light Accuracy Measured? 

Color Rendering Index (CRI) is an accuracy measurement of white light. The sun is the standard for 100 on the CRI scale. Average LEDs are typically 80 on the CRI scale which is rated between 0 to 100.  An LED of 90 CRI or more is the mark of high quality light rendering.

Comparison of  80, 90, and 100 CRI

These pictures a show a comparison of  80, 90, and 100 on the color rendering index (CRI)


  • CCT: Correlated Color Temperature (This can also be called “adjustable white”).  This is a technology where there are two adjacent LED chips; one is lower Kelvin temperature and the other is high. The two chips can be blended via controls. This is a great option for color temperature flexibility.
  • RGB: Red, Green, and Blue. This technology is a single LED chip with a section that is red, green, and blue. These colors can be mixed with a controller to make all the colors of the rainbow. This is a great option for fun and unique lighting effects.
  • RGBW: Red, Green, Blue, and White. This technology combines the best of worlds. It has LED chips with a red, green and blue section, as well as a dedicated white chip for full spectrum accuracy. These can be blended together or selected via a controller.
  • CRI: Color Rendering Index. This scale measures the accuracy of white light on a scale from 0 to 100. While average LED lights typically score around 80 on the CRI scale, those with a CRI of 90 or higher boast exceptional light accuracy.

Conclusion

Understanding the complexities of light color is essential in the realm of LED lighting selection. Light perception involves a spectrum of electromagnetic radiation with varying wavelengths, each contributing to the rich variety of colors perceived in the world. The mix between these wavelengths not only affects the ambiance created but also influences the practical applications of LED lights. From warm, inviting colors to crisp, neutral tones, the choice of light color can significantly impact the mood and functionality of a space. Moreover, considerations such as color rendering accuracy, measured by the Color Rendering Index (CRI), further underscore the importance of selecting the right lighting solution.




References:

1. Science Mission Directorate. "Visible Light" NASA Science. 2010. National Aeronautics and Space Administration. [5 May, 2024] http://science.nasa.gov/ems/09_visiblelight