Over millions of years, the environment and its development have shaped the human eye and conditioned our reactions to ambient light.
2 factors determine good colour vision:
The perception of light by the eye:
The eye sees colours in a differentiated way. Each colour is associated with a wavelength which we perceive to a greater or lesser extent. Consequently, we are very sensitive to yellow, and see blues and reds poorly..
Perception of colours by the human eye:
The nature of light: it is light which makes colours visible
For example, a “blue” surface only reflects the colour blue. Thus, when you go through a road tunnel lit by “orange” lamps, a blue car will look black. In fact, these street lights contains no blue; the blue body of the car in question will therefore not reflect any wavelength and will consequently be seen as black by the eye.
The same phenomenon applies in the dental sector, particularly in terms of the choice of colour under an artificial light: the absence of certain colours (blue for example) under this light will adversely affect the practitioner’s perception of the natural colour of the tooth and that of his colour reference set. He will then run the risk of selecting the wrong colour. Once his patient has left the dental practice and observes his artificial tooth under daylight, he will notice a difference in colour with his natural teeth…
The nature of light is described using two measurements
The colour rendering index (CRI), which is expressed as a percentage: A CRI of 100 indicates that the light in question contains 100 % of the existing colours. Daylight has a CRI of 100.
Colour temperature, measured in degrees Kelvin: the higher this is, the more the light in question “contains large quantities” of colour.
So daylight, which varies during the day, is defined in international standards as being at 6,500 °K and 100% CRI.
Artificial light in a dental practice or laboratory is defined as follows in accordance with DIN 67 505:
It must contain a maximum of colours visible to the eye (minimum IRC of 90)
It must be very “white”, like daylight (at least 5,000 K)
Wavelength and colour temperature
The curve at the top of the graph below describes light with a high colour temperature (> 5,000 °K). This trend of this curve, which is “flat”, is explained by the fact that all the colours are represented in it in equal “quantities”.
To the contrary, the bottom curve is representative of light which contains almost no purple (in terms of purples and blues, the curve is at low levels (< 1,000 °K) but it has a relatively large amount of yellow and red. This, for example, is the result with light from a yellow bulb.
Under “low” light, the eye will see:
Blues poorly: There are few of them in this light and the human eye sees them poorly.
Yellows well: There is a fair amount of them in light and the human eye sees them well
Reds well: Although the eye does not perceive them very well, this is compensated for as light features a lot of them
How does the eye see light?
Over millions of years, the environment and its development have shaped the human eye and conditioned our reactions to ambient light.
2 factors determine good colour vision:
The perception of light by the eye:
The eye sees colours in a differentiated way. Each colour is associated with a wavelength which we perceive to a greater or lesser extent. Consequently, we are very sensitive to yellow, and see blues and reds poorly..
Perception of colours by the human eye:
The nature of light: it is light which makes colours visible
For example, a “blue” surface only reflects the colour blue. Thus, when you go through a road tunnel lit by “orange” lamps, a blue car will look black. In fact, these street lights contains no blue; the blue body of the car in question will therefore not reflect any wavelength and will consequently be seen as black by the eye.
The same phenomenon applies in the dental sector, particularly in terms of the choice of colour under an artificial light: the absence of certain colours (blue for example) under this light will adversely affect the practitioner’s perception of the natural colour of the tooth and that of his colour reference set. He will then run the risk of selecting the wrong colour. Once his patient has left the dental practice and observes his artificial tooth under daylight, he will notice a difference in colour with his natural teeth…
The nature of light is described using two measurements
So daylight, which varies during the day, is defined in international standards as being at 6,500 °K and 100% CRI.
Artificial light in a dental practice or laboratory is defined as follows in accordance with DIN 67 505:
Wavelength and colour temperature
The curve at the top of the graph below describes light with a high colour temperature (> 5,000 °K). This trend of this curve, which is “flat”, is explained by the fact that all the colours are represented in it in equal “quantities”.
To the contrary, the bottom curve is representative of light which contains almost no purple (in terms of purples and blues, the curve is at low levels (< 1,000 °K) but it has a relatively large amount of yellow and red. This, for example, is the result with light from a yellow bulb.
Under “low” light, the eye will see: