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Design. with coloured light

Designing with white light colours and coloured light

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.

Colour

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.

Colour

Body colour

The body colour ârises as a result of the incident light and the specific absorption properties of the surface. Therefore, the tri-stimulus value of a body colour can only be determined in combination with the type of light with which it is illuminated. In addition to hue, brightness and saturation, the body colour of an object is also defined by the reflectance. When illuminating coloured walls or objects with coloured light, the reciprocal effect of light colour and body colour is paramount. This interplay is the basis of subtractive colour mixing. The chromatic effects can be intensified or altered.

Coloured highlighting

Coloured accent lighting and coloured background lighting changes the effect of objects in the room. The colour saturation of the object increases in the foreground when the background brightness is decreased. Blue colours seem to recede into the background, while the chromatic effect makes magenta come to the fore.

Lighting effects can be intensified using coloured light. Strong colour contrasts increase the brightness contrasts. High brightness contrasts likewise increase the colour contrasts. Natural overall effects arise due to warm colours of light and filter colours such as "Skintone", magenta and amber, or due to cold colours of light such as sky-blue and night-blue.

Coloured accent lighting is used for
- exhibitions
- trade-fair stands
- sales areas

Colour systems

CIE system

In the CIE standard colorimetric system, body colours and light colours are represented in a continuous, two-dimensional diagram. The spectral constitution of light colours results from the type of light, while that of body colours results from the type of light and the spectral reflectance or transmittance. The dimension of brightness is left unconsidered here; this means that only the hue and saturation of all colours can be determined in the diagram. The coloured area is enclosed 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. Complementary colours are located opposite each other in the CIE model and combine to form white.

Munsell system

In the Munsell system, body colours are arranged according to the criteria of brightness, hue and saturation to produce a complete sample catalogue in the form of a three-dimensional matrix. Brightness here refers to the reflectance of a body colour; the hue refers to the actual colour, while the term saturation expresses the degree of coloration, from the pure colour down to the uncoloured greyscale. Whereas a two-dimensional diagram is sufficient for colours of light, a three-dimensional system is required for body colours due to reflectance.

Colour of light

Colour of light Colour of light Colour of light

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.

Colour of light

Colour of light Colour of light Colour of light Colour of light Colour of light Colour of light Colour of light Colour of light

Amber

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.

White light

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.

Coloured light

Coloured light is used for
- exhibitions
- trade-fair stands
- sales rooms
- event lighting

Colour mixing

Colour mixing Colour mixing Colour mixing Colour mixing

Light colours
Super imposing several colours of light is an additive mixing process. Mixing two of the primary colours red, green and blue results in magenta, cyan or yellow. By mixing the three primary colours in equal amounts, white light is produced.

Light colour and body colour

Subtractive colour mixing occurs when coloured surfaces are illuminated with coloured light. Mixing two of the subtractive primary colours magenta, cyan and yellow, produces the additive primary colours red, green or blue. Warm body colours are emphasised by a warm white colour of light. Cold body colours appear brighter and more saturated under cold neutral colours of white light, especially daylight white.

The appearance of a body colour can seem more saturated and brighter when the lighting on it is of similar colour. Body colours appear less saturated, or darker, when the coloured lighting is dissimilar. The actual appearance of the results of subtractive colour mixing depends on the spectral constitution of the components being mixed.

Colour mixing Colour mixing Colour mixing Colour mixing

Colours of light

Super imposing several colours of light is an additive mixing process. Mixing two of the primary colours red, green and blue results in magenta, cyan or yellow. By mixing the three primary colours in equal amounts, white light is produced.

In practice, when illuminating coloured surfaces, it is recommendable to perform lighting tests or calculations. The same applies to the use of colour filters.

Colour rendition

The quality of the reproduction of colours is termed colour rendition. Linear spectra have a very good colour rendition. Linear spectra only permit one single colour to be perceived well. Multiline spectra reproduce several colours of the relevant spectrum well, but in the intermediate areas the colour rendition is weaker. Blue and green colours appear comparatively grey and matt under warm white incandescent light despite excellent colour rendition. However, these hues appear clear and bright under daylight white light from fluorescent lamps - despite poorer colour rendition. When rendering yellow and red hues, this phenomenon of respective weakening and intensifying of the chromatic 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.

Colour rendition

Linear spectrum

Colour rendition

Continuous spectrum

Colour rendition

Multiline spectrum

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 effect

Colour effect

- Red is the colour of fire and the expression for power, warmth and energy. The colour has a dominant effect. Where pale red is concerned, the aspect of warmth decreases while its lightness increases.
- Yellow is the lightest colour in the colour wheel, but used in the foreground it does not have the same energy as red.
- Blue is the colour of the sky and is one of the cold colours which gives an effect of depth. Dark navy blue has a rather melancholy effect, whereas blue-green emanates peace.
- Green is the colour of vitality. Its nuances range from calming to refreshing.
- White is one of the non-colours and is the polar opposite of black. White stands for purity.
- Black stands for darkness and appears sinister and negative.
- Grey is one of the non-colours and appears indifferent.

Colour effect

The effect of colours is explained from the physiological point-of-view of actually seeing colour and the psychological aspects of sensory perception. The lure of colours triggers associations and is interpreted in the context of the social and cultural environment. The different hues belonging to a colour can, in turn, also have other effects. The effect of individual colours can be increased by way of a colour contrast.

Colour effects are particularly important for
- exhibitions
- trade-fair stands
- sales areas
- restaurants

Colour contrast

Colours themselves

The seven colour contrasts originated from the colour theory of Johannes Itten. This approach is not based on physical and chemical properties of colours, but on their subjective effects.

The primary colours yellow, red and blue produce the strongest contrast. The colour contrast becomes weaker with secondary or tertiary colours or as the saturation decreases.

Light-dark

The "non-colours" black and white produce the strongest contrast. Even with the "proper" colours, their effect is significant. A light colour next to a dark colour has a stronger effect than next to an equally light or lighter colour. The effect of hues can be intensified by greater differences in brightness.

Cold-warm

In the colour wheel, the warm colours with red and yellow components are located opposite to the cold blue hues. Green and magenta form the neutral transitions. The effect of a predominant colour can be increased when combined with an accent from the opposite colour.

Simultaneous

The effect of the simultaneous contrast has its origin in how the eye processes perception. After staring at a colour for a long time and then looking at a neutral grey, the eye forms a simultaneous contrast colour. Red leads to a green tinged grey shade. Green causes a grey area with a red tinge to appear. Colours change their effect due to the influence of the surrounding colours.

Complementary

The pairs of colours lying opposite in the colour wheel form the complementary contrast from a primary colour and the secondary (mixed) colour made of the other two primary colours. Yellow-violet displays the largest light-dark contrast, orange-blue the largest cold-warm contrast. Red-green have the same light intensity. The complementary contrast causes the brilliance of the colours to increase.

Quality

The quality contrast, or intensity contrast, describes the distinction between pure colours and murky colours. Mixing pure colours with grey shades makes the former murky and dull, and the quality of colour purity is lost. Pure colours have a dominating effect over murky colours.

Quantity

The quantity contrast refers to the relationship of the size of one coloured area with the next. A large coloured area with a small area in a contrast colour increases the chromatic effect of the main colour.

Ambient colours

White light that is reflected by a coloured surface takes on the colour of the surface and becomes the predominant colour of light for the whole room. When lighting a coloured wall with coloured light, this effect can be increased, reversed or inverted.

The colour of light in a room is influenced by the decoration of the room. In comparison to diffuse light, direct light increases the effect of the light when illuminating a coloured surface. The effect of a body colour can be intensified by using coloured light of a similar colour. Strong colour contrasts appear brighter for the same illuminance than a weaker colour contrast. Lesser colour contrasts can be perceived better under brighter lighting. Within closed rooms the effect is hardly perceptible due to the phenomenon of colour constancy.

In practice, when illuminating coloured surfaces, it is recommended that lighting tests or calculations be carried out.

Coloured accent lighting is used for
- exhibitions
- trade-fair stands
- sales areas

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