The colour of the light emitted by a lamp. The colour of light can be expressed by using xy coordinates to specify a colour locus in the chromaticity diagram. White light colours can also be expressed as a colour temperature, and can also be broadly categorised as either warm white (ww), neutral white (nw) and daylight white (dw). The same colours of light can have different spectral distributions and a correspondingly different colour rendition.
Colour is a significant component of visual perception. It cannot be perceived without daylight or artificial lighting. The combination of lamps and filters allows a multitude of design possibilities for emphasising or altering the lighting effect of rooms and objects with coloured light. The term "colour of light" covers both white and coloured light. Warm white, neutral white and daylight white are derived from the white colour of light. The coloured light covers the entire visible spectrum.
Light colour
The light colour refers to a colour which is emitted by a light source. The light colour is produced as a result of the emitted spectrum of light. The type of light colour is defined by hue, saturation and brightness. Using filters produces coloured light. This enables the colouration of rooms to be modified without changing the rooms physically. Mixing several light colours is referred to as additive colour mixing.
The higher red component in warm white light allows rooms to appear warmer than with neutral white light. The higher blue component in daylight white light creates a cooler atmosphere.
Warm colours of light are preferred above all at lower illuminances and with directed light, whereas cold colours of light are accepted at high illuminances and diffuse illumination. White light is described by specifyingthe colour temperature, colourrendition, chromaticity location and spectrum. The white colour temperature is divided into three main groups: warm white, neutralwhite and daylight white. A good colour rendition with the lighting will only produce a low colour deviation. The chromaticity location identifies the colour within the CIE diagram.
Compared to the primary colours yellow, blue and red, the colours amber and magenta appear weaker in their expressiveness. Yellow and red colours of light create a warm atmosphere in a room. Blue colours of light allow a room to give a cooler impression.
In architectural lighting, colours from the daylight spectrum are felt to be natural: magenta (conditions of light at sunset), amber (atmospheric light at sunrise), night blue (clear night sky) and sky blue (light of the sky by day). For coloured light, the data concerning chromaticity location and spectrum are important. The chromaticity location is specified by the co-ordinates in the CIE diagram, whereby a colour of light can be formed by different colour spectra.
Sony Center, Berlin
Glass pavilion, Glass technical college, Rheinbach
Hong Kong and Shanghai Bank
ERCO, Lüdenscheid
On presentation lighting, making specific use of colours of light allows luminous colours to be achieved on the objects being illuminated. Daylight white light is often used in office rooms to augment the daylight.
ERCO P3, Lüdenscheid
Zürich Insurance, Buenos Aires
Teattri Ravintola, Helsinki
Teattri Ravintola, Helsinki
The colour of the light emitted by a lamp. The colour of light can be expressed by using xy coordinates to specify a colour locus in the chromaticity diagram. White light colours can also be expressed as a colour temperature, and can also be broadly categorised as either warm white (ww), neutral white (nw) and daylight white (dw). The same colours of light can have different spectral distributions and a correspondingly different colour rendition.
Light colour is the colour of the light emitted by a lamp. Light colour can be expressed using x,y coordinates as chromacity coordinates in a standard colorimetric system, or, for white light colours, it can also be given as the colour temperature TF . In the CIE standard colorimetric system, the colour of light is calculated from the spectral constitution and represented in a continuous, two-dimensional diagram. The hue is defined via the chromaticity co-ordinates of the spectral colour and via the saturation level. The design of the diagram features a coloured area that contains every possible real colour. The coloured area is encompassed by a curve on which the chromaticity locations of the completely saturated spectral colours lie. At the centre of the area is the point of least saturation, which is designated as a white or uncoloured point. All levels of saturation of one colour can now be found on the straight lines between the uncoloured point and the chromaticity location in question. Similarly, all mixtures of two colours are likewise to be found on a straight line between the two chromaticity locations in question.
Planck's curve contains the chromaticity locations of Planck's radiation of all temperatures. Since the chromaticity location of a light source often lies near to the curve, starting from the curve of Planck's radiator, a host of straight lines of the closest colour temperatures is added. With their help, even those light colours that are not on this line can be identified by the closest colour temperature. On temperature radiators, the closest colour temperature corresponds to something approaching the actual temperature of the lamp filament. On discharge lamps, the closest colour temperature is stated.
Main groups colour temperatures
In addition, white colours of light are divided into three main groups: the warm white range (ww) with the closest colour temperatures below 4000 K, the neutral white range (nw) between 4000 and 5000 K and the daylight white range (dw) with the closest colour temperatures over 5000 K. The same colours of light may have different spectral distributions and a correspondingly different colour rendition.
