Color Rendering Index

Also CRI; a quantitative measure of the ability of a light source to reveal the colors of objects faithfully in comparison with an Standard Illuminant or ideal light source (e.g. D65). Light sources with a high CRI are desirable in color-critical applications such as neonatal care, art restoration or administering Colorblind Tests like the Ishihara Test.

While human Color Constancy can largely compensate for the color of the illuminant, there is no mechanism for compensating for the CRI, so high CRI Illuminants are usually preferred in all applications, if practical.

The CRI of a light source is unrelated to the apparent color of the light source. The CRI is determined by the light source’s Emission Spectra: fluorescent bulbs have very low CRI compared to LEDs, Incandescent or Halogen bulbs because of their jagged Emission Spectra.

The Emission Spectra of modern LEDs are smoother than for fluorescent lights, and therefore have a higher CRI.