All You Need to Know Color Spectrum of LED and the Color Rendering Index (CRI)
Color Rendering Index (CRI)
CRI is defined as how a light source makes the color of an object appear to human eyes and how well subtle variations in color shades are revealed. It’s really how well a light bulb shows true colors. The Color Rendering Index (CRI) is a scale from 0 to 100 percent. It indicates how accurate a given light source is when it comes to rendering color when compared to a reference light source. The better color rendering ability depends on higher CRI.
Color temperature or Kelvin of light
Before we learn about the color spectrum of lights, we should know about the color temperature. LED color temperature measures the color of a LED light bulb. It defines the amount of pure white, yellow, red and blue color in a light. Another way to think of the color temperature is how 'warm' or 'cool' is the white LED light bulb. Color temperature is measured in degrees Kelvin and is a measure of the part of the color spectrum that is found in light.
There is no right or wrong in Kelvin, its a personal choice. Typically warmer 3000K is used in homes,. 4000K is offices and larger areas and 5000K in warehouses and outdoors. We no longer recommend above 5000K. The American medical association has stated that it is dangerous to your health.
Color Spectrum of Lights
The light emitted by the sun includes a wide range of colors. While the sunlight appears white to us, this sunlight when viewed through a prism creates a spectrum of colors including violet, blue, green, yellow, orange and red. Those are listed by wavelength from short to longest. These colors merge to create the white light that is visible to us. The sun also includes invisible light from ultraviolet radiation.
Light bulbs create colors in different ways, most of them use a combination of the 6 colors to create the light. Almost none of them use all 6. Most create the light with a few and then may add diffusers of other colors.
Wide spectrum lights are really only important for grow lights and even then you typically need a few different ones to create the full spectrum.
Importance of CRI
The importance of CRI can be established from the fact that it makes the color appear more natural. The CRI makes it easier for your eyes to see these colors. It also helps identify the different colors at depth which improves depth perception. Higher CRI in your home LED Downlights generally more enjoyable light. Good CRI in LED floodlights is still important.
Each type of bulb has a different range. The incandescent bulbs have a 98+ score. The HID bulbs, however, have the lowest range which is only 20. the metal halide bulbs have a score of approximately 60. Older LEDs had a score of about 50. The modern LED Corn Bulbs, however, are best in this regard as well. Today, the LEDs have a score ranging from 80 to 90 and more making them a great LED replacement for 400 watt Metal Halide.
80-89 CRI = Very Good
70-79 CRI = Good
40-69 CRI = Poor
0-39 CRI = Very Poor
Color Spectrum vs. CRI
CRI is a vast term but focuses on the color rendition. CRI is the measure of the ability of a light source to accurately condense all frequencies of its color spectrum when compared to a perfect reference light of a similar type. Color Spectrum focuses on the wavelength of light and is less important for home or commercial lighting.
in choosing LED lighting, having the full color spectrum is not as important as a good CRI and a Kelvin level that you enjoy.
LEDs are the most advanced form of a light bulb. They are capable of producing more lumens of light, and they are available in different temperatures. Today they have strong CRI scores and an ever improving color spectrum.