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= Color Rendering Index  =

== Definition ==
The Color Rendering Index (CRI) is a quantitative measure of a light source's ability to reveal the colors of objects faithfully in comparison with an ideal or natural light source. It is expressed on a scale from 0 to 100, where 100 represents the most accurate color rendering. CRI is critical in lighting design, photography, art, and various industries where color accuracy is essential.

Key characteristics of CRI include:
* Measures how well a light source displays the colors of an object compared to a reference light source
* Calculated by comparing the color of objects under the test light source to their color under an ideal light source
* Ranges from 0 to 100, with higher numbers indicating better color rendering

== Technical Overview ==
The CRI is determined by measuring the color shift of eight standard color samples when illuminated by the test light source compared to a reference source (typically sunlight or an incandescent lamp). These color samples represent different hues and saturations:
* Ra: The general color rendering index calculated from the first eight color samples
* Extended CRI (Ra16): Includes additional color samples for more comprehensive analysis

== Examples ==
Different light sources have varying CRI values:
* Incandescent bulbs: Nearly 100 CRI (excellent color rendering)
* Fluorescent lights: Typically 50-80 CRI (moderate color rendering)
* LED lights: Can range from 70 to 95+ CRI (depending on the specific type)
* Sodium vapor lamps: Very low CRI (around 20-30)

[[Image:low-cri-light-calm-technology.png|left|300px]]

[[Image:high-cri-light-calm-technology.png|left|300px]]


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== Practical Applications ==
CRI is crucial in various fields:
* Art galleries and museums
* Photography and film lighting
* Architectural and interior design
* Medical and scientific laboratories
* Retail display lighting

== Limitations ==
While CRI is widely used, it has some limitations:
* Does not account for the full spectrum of color perception
* Does not measure color temperature or spectral distribution
* May not perfectly represent how humans perceive color in all conditions

== References ==
# International Commission on Illumination (CIE) publications
# Lighting research publications
# Manufacturer specifications for light sources
# https://www.ies.org/definitions/color-rendering-index-cri-of-a-light-source/ 

[[Category:Light]]
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