Color rendering
The color rendering of a light source refers to its ability to reveal the colors of various objects faithfully in comparison with an ideal or natural light source. Light sources with good color rendering are desirable in color-critical applications such as neonatal care and art restoration. It is defined by the International Commission on Illumination (CIE) as follows:[1]
Color rendering: Effect of an illuminant on the color appearance of objects by conscious or subconscious comparison with their color appearance under a reference illuminant.
A wide variety of quantitative measures have been devised to measure the color rendering of a light source, to the human eye or to the camera. Notable ones include:
- Color rendering index (CRI), CIE 1995. Currently acknowledged as flawed, but still widely used for consumer lighting. Updated 1999, but rarely followed.
- Television lighting consistency index (TLCI), EBU 2012. Address the spectral response of cameras and screens, which can have significantly different results with high-CRI LED lighting.[2]
- Spectral similarity index (SSI), AMPAS 2016 (revised 2020). Ditches the concept of color samples in CRI and TLCI to directly address the shape of the spectrum. Published as SMPTE 2122.[3]
- IES TM-30, 2015 (revised 2020). A spiritual descendant of CRI with updated color transformation, more (99) color samples, and scoring for additional factors such as gamut size and hue shift. Still uses human participants. Endorsed by CIE in 2015 to replace CRI.[4]
References
- ^ "CIE 17.4-1987 International Lighting Vocabulary". Archived from the original on 2010-02-27. Retrieved 2008-02-19.
- ^ "Television Lighting Consistency Index 2012". tech.ebu.ch. 31 May 2016.
- ^ "Spectral Similarity Index (SSI)". Oscars.org | Academy of Motion Picture Arts and Sciences. 21 April 2017.
- ^ Michael Royer (March 31, 2016). "Evaluating Color Rendering With TM-30" (PDF). ENERGY STAR Webinar (US DOE).