An identical light temperature does not automatically imply the same light. Colour rendering of any light source depends upon the composition of the light, i.e. the colour of which the light is built up. To assess these values, the Color Rendering Index (Ra or CRI) has been introduced: Indexing of the brightness of a light source.
CRI 100 (100%) is the highest possible score; all colours are rendered optimally. A lower CRI value indicates that the colours are rendered less clearly. This is because at a lower CRI, colours are rendered duller than they are, as can been seen on the picture.
Please refer to the average CRI values below:
|Type of lamp||Colour temperature||CRI|
Any person experiences his or her personal sensation of colour temperature and its rendering. This is called retinal sensitivity and all light units can therefore be interpreted in different ways.
Retinal sensitivity means: the average sensitivity of the human eye for different colours (wave lengths). This is determined by three types of light-sensitive cells that are called receptors or cones. These cones are especially well-represented within the yellow part of the spectrum.
This is the area where the optical axis of our eye lens converges with the retina. Our eyesight is therefore highest in this yellow area. This is not the same for everybody, which gives rise to the occurrence of different preferences. Aided by testers in a shop you yourself will have to decide which light accords with your own preference.