What is CRI?

When deciphering the terminology you'll come across when searching for LED lighting, color rendering index (CRI) measures how accurately a light source makes the color of an object appear to its true color.  This information is important where color accuracy is vital, such as portrait studios, retail stores, hospitals, medical and commercial offices, display cases, and warehouses.

The CRI runs on a scale of 0-100, and the higher the index number, the better light source is at rendering color. Light sources with a CRI of 85-90 are good, while 90 is excellent. CRI is dependent on color temperature as the hue of the light cast can affect perception of the object's color. A 2700 Kelvin warm color temperature has s CRI of 100. Brighter, "sunlight" color temperatures closer to 5000 Kelvin have CRI's of 75-90.

CRI was created by the International Commission on Illumination (CIE), a lighting standardization body, to define how accurately a light source reveals the true colors of objects, people, and surroundings. Reference lights are chosen based on the correlated color temperature (CCT) of the light that is being tested. The reference light is a blackbody (incandescent) if the light source has a CCT of less than 5000 Kelvin, and if CCT is more than 5000K, the reference light is daylight. The average differences in chromaticities are subtracted from 100 (the CRI of daylight and incandescent light), and that number is defined as the CRI of the light source.  A light source with a CRI close to 100 shows colors very similarly to how its reference light shows those same colors.  High-intensity discharge (HID) lights typically have a CRI rating close to zero; fluorescent lights have a range in the lower 60s and below, and LED CRI's can range from 70 to 98.  Accurate color rendering can be achieved with a high-CRI light strip, recessed lighting, globe bulb, linear light , or other high-CRI bulb fixture.

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