15 11月 2015

What is CRI?

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CRI stands for Colour Rendering Index and in simple terms, based on a figure from 0 to 100; it is the measurement of the ability of light sources to accurately reproduce colours in comparison to a standard reference source. The higher the CRI rating the better the light source is at accurately reproducing every colour of the spectrum. There should be no excessive excess or loss of any colour generated from the lamp in order that illuminated objects appear naturally.

Colour Rendering

Since 1931, when the first system ofmeasuring colour rendering was formalised by the CIE (Commission Internationale de l’Eclairage = International Commission onIllumination), the lighting industry hasbeen able to communicate the qualityof its light to specifiers and end usersalike.

The Color Rendering Index (CRI or Ra)is a quantitative measure, which rates a light source’s ability to reproduce
the colours of objects faithfully. In order to objectively compare the

colour rendering properties of any
light source, the CIE’s standardised measuring method operates on a scalefrom 0 to 100 (poor to excellent). Thecolour change of 14 standard colours is calculated when an object is exposedto a specific light source and then thisis compared to a reference illuminant of the same colour temperature (a black body* is used for colour temperaturesup to 5000K and daylight above that).The CRI for a pair of light sources can only be compared if they have the same colour temperature.

The first eight, non-saturated colours(R1 – R8), are used to calculate thegeneral CRI and the remaining 6 saturated colours (R9 up to R14) supplyadditional information about the colour rendering properties of the light source with respect to the more vivid, saturated colour.

The CRI scale is chosen so that an ideal black body source, such as incandescent or halogen lamps, is bydefinition a CRI rating of 100. For lightsources emitting a discrete spectrum,

like LED and discharge lamps, the CRIcan be anywhere between 0 – 100. Asa rule of thumb, the more the spectrumis filled at all wavelengths (380 – 760nm), the better the colour renderingproperties of the source, however a high CRI measurement intrinsicallymeans lower efficacy (as less efficientwavelengths are also represented inthe spectrum).

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One Response to What is CRI?
  1. Hablando del aceite de canola, también deberías hacer una entrada especial, tan solo a los aceites vegetales comestibles, como el de soya, palma, maíz.. muy buena inomcfarión, gracias por compartirla!


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