Your free myERCO account allows you to mark items, create product lists for your projects and request quotes. You also have continuous access to all ERCO media in the download area.


You have collected articles in your watchlist

Technical environment

Technical environment

Global standard 220V-240V/50Hz-60Hz
Standard for USA/Canada 120V/60Hz, 277V/60Hz
  • 中文

Our contents are shown to you in English. Product data is displayed for a technical region using 220V-240V/50Hz-60Hz.

Colour rendition

The quality of how colours are reproduced is called colour rendering. Line spectra have very good colour rendering. Line spectra allow only a single colour to be perceived well. Multi-line spectra render several colours of the respective spectrum well, but colour rendering is weaker in the intermediate ranges. Blue and green colours appear comparatively grey and dull in warm white incandescent light despite excellent colour rendering. However, these colour tones appear clear and luminous in the light of daylight white fluorescent lamps – despite poorer colour rendering. With the rendering of yellow and red colour tones, this phenomenon of weakening or intensifying of the colour effect is reversed.

Because the eye is able to adapt to light of the most different colour temperatures, the colour rendition must be determined dependent on the colour temperature. Tungsten halogen lamps feature very good colour rendition. The rendition quality of fluorescent lamps and metal halide lamps ranges from good to average. The degree of colour distortion against a reference light source is indicated using the colour rendition index Ra or the colour rendition grading system. The colour rendition index is only used for white colours of light.

Would you like to find out more?

Colour rendition Colour rendition
Colour rendition

The same colours of light can produce a different rendition of a body colour due to different spectral constitution. Continuous spectra lead to a unifrom colour rendition. Linear spectra only correctly render a very small colour range. Multiline spectra are compiled from different linear spectra and thus improve the colour rendition. The more spectra can be bound to one linear progression, the better the colour rendition. Incandescent lamps feature a linear spectrum, while discharge lamps have a multiline spectrum.

Colour rendition

Very good colour rendition is important for
  • exhibitions
  • trade-fair stands
  • sales rooms
  • offices
  • workstations

Colour rendition

Colour rendering describes the change in the colour impression under a given illumination compared to a reference light source. The general colour rendering index CRI is usually used for evaluation purposes – the maximum value of 100 means no change. A comparable light source with a continuous spectrum is used as a reference light source, whether this is a thermal radiator of comparable colour temperature or daylight.

Colour rendition

To enable the colour rendition of a light source to be determined, the chromatic effects of a scale of eight body colours viewed under the type of illumination being scrutinised and also under the reference illumination are calculated and related to each other. The resulting quality of colour rendition is expressed in colour rendition indices; these can relate both to the general colour rendition (Ra) as an average value or to the rendition of individual colours. The maximum index of 100 signifies ideal colour rendition as experienced with incandescent lamp light or daylight. Lower values refer to a correspondingly worse colour rendition. Linear spectra of light lead to good colour rendition. Linear spectra in general lead to a worse rendition. Multiline spectra are composed of several different linear spectra and improve the colour rendition.

Would you like to find out more?

Further topics on lighting technology

Do you need further information?

You can contact your regional contact partner via:

You can gladly send us an e-mail or ask your question here

Your data will be handled confidentially. For further information see Data protection declaration.




Planning light

About ERCO