What Is CRI (Color Rendering Index)?August 11, 2016 –Posted in: Lighting Information, Uncategorized
If you ever look through lighting catalogs, you might have noticed “CRI” in the tech specs. CRI stands for Color Rendering Index and it’s a measure of the quality of color light. Basically, it measures how accurately a given LED light represents the true color of what you’re looking at. An excellent CRI is considered to be anything above 90, a very good above 80 and anything below 70 is considered to not accurately represent color. If your shopping for a light, anything about 80 should be more than enough unless you work at a print ad agency. The color temparture of the light source goes hand in hand with CRI. Color temperature is measured in Kelvin, and typically ranges from Infrared (0) at to Ultraviolet (above 20,000) although lighting typically ranges from 2500k to 6800k .
A high CRI rating doesn’t always mean that a light source accurate at representing colors, several other factors can throw the CRI off, like the reference point itself which tools are calibrated with. Along with that, the scale itself has gotten massive criticism for not always correlating when testing white LED’s or fluorescent fixtures. Typically CRI is not something you will ever notice as most bulbs come with a fairly high rating.
How is CRI actually measured?
CRI can be measured in a very simple, yet not so accurate way, at home.
Step 1 – Take a color chart outside into direct sunlight
Step 2 – Set you camera into daylight mode – this will be your reference point.
Step 3 – Use a gray card to set exposure (50 IRE), and take a photo of the color chart.
Step 4 – Repeat the process with your light source.
Step 5 – Compare color differences to see how vast they are. You could get 80, 90, and 95 measured CRI bulbs to have further reference points at different CRI levels.
Just remember that no light source has perfect CRI, unless you managed to fit a piece of the sun into your fixture.