A Computational Tool for the Use of Colour Harmony Rules in Facade Design
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presentation at eCAADe 2007, 26-28 sep 2007, Frankfurt am Main, Germany The quality and availability of exterior paints has led to a new vernacular use of colour in Ireland and Scotland. Communal colour designs highlight the conflict between individual colour preference and the community desire for harmony. This is often expressed as a fixed colour design by an individual designer. The provision of the widest possible range of colour designs, all of which express communal harmony, can help to accommodate individual preferences. This project uses computation to apply colour harmony rules within a chosen environment and to generate all the possible colour combinations which conform to these rules. The Colour Combinations program uses two steps to establish a colour design: palette selection and colour combination. The harmony rules can be adjusted for each step depending on the context for the design or the type of colour combination required. Once an appropriate palette has been selected all possible colour combinations for a terrace of six houses are generated. Each combination is then tested for harmony and the number of combinations which conform to the specified rules is displayed. Each harmonious combination can then be displayed in turn for manual selection. The program allows the effects of adjusted harmony rules to be tested and examined quickly. This could allow individual colour preferences to be accommodated within a communal colour design.
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A Computational Tool for the Use of Colour Harmony Rules in Facade Design
- 1. A Computational Tool for the Use of Colour Harmony Rules in Facade Design Sally Semple Scott Chase eCAADe 2007 Department of Architecture
- 4. Burano
- 5. Contemporary reinterpretation of a historic palette Torino
- 6. wall 1 H:13 / S:88 / L:104 wall 2 H:20 / S:141 / L:146 balcony H:26 / S:94 / L:120 wall 3 2 H:21 / S:144 / L:156 balcony H:29 / S:104 / L:167 wall 4 3 H:22 / S:135 / L:164 balcony H:31 / S:92 / L:180 wall 5 4 H:29 / S:177 / L:164 wall 6 H:30 / S:151 / L:174 Chateau-Double apartments (Lenclos)
- 7. Dulux paints
- 8. Identity Similarity Contrast Complementary Non-complementary colours colours Colour harmony
- 9. Variation in value Variation in Variation in hue only saturation only only (0-20) (0-10?) (0-100) Pleasing intervals Identity from 0 to a just from 0 to a just from 0 to a just noticeable difference noticeable difference noticeable difference Similarity from 0.5 to 1.5 from 3 to 5 from 7 to 12 steps Contrast from 2.5 to 10 7 or over from 28 to 50 steps Displeasing intervals 1st ambiguity from a just noticeable from a just noticeable from a just noticeable difference to 0.5 difference to 3 difference to 7 2nd ambiguity from 1.5 to 2.5 from 5 to 7 from 12 to 28 steps glare more than 10 Moon & Spencer: Colour harmony rules
- 10. Context Materials Light Culture Other factors
- 12. Variation in Variation in Variation in hue value only saturation only only (0-255) (0-255) (0-128) Pleasing intervals Identity from 0 to 5 from 0 to 10 from 0 to 5 Similarity from 12 to 40 from 50 to 90 from 18 to 30 Contrast over 60 over 120 from 70 to 128 Adaptation of Moon & Spencer to Windows HSL
- 13. RGB vs. Munsell systems
- 14. Two step process 1. Generate the colour palette 2. Generate the set of colour combinations Parameters – Undesirable hue ranges – Identity level – Similarity range – Contrast level – Step (granularity) – Manual settings for • Roof, tree, bush colour • Individual house saturation & value Colour Combinations software
- 16. Design for contrast: “Burano” palette
- 17. Design for integration: “Chateau-Double” palette
- 19. • Harmony definitions limited to hue • Excessive computation time when more than 50 hues • High knowledge of colour harmony and systems needed to adjust variables and interpret results • Conflict between Munsell and HSL colour systems produces distortions in harmonies • Manual selection and development required to produce useable designs Limitations
- 20. • Input by colour rather than number • Output format to allow better assessment of scheme in context • Allow variety of different facade forms rather than single example • Use different elements to establish context or provide unifying colour • Fix specific colours within a scheme or limit specific elements to their own palettes • Specify patterns or rhythms within a colour scheme • Allow variation in saturation and value • Address relative complexity of the design involving form and area of design elements • Use a more perceptually accurate colour system than HSV Possible further development
Notas del editor
- Abstract. The quality and availability of exterior paints has led to a new vernacular use of colour in Ireland and Scotland. Communal colour designs highlight the conflict between individual colour preference and the community desire for harmony. This is often expressed as a fixed colour design by an individual designer. The provision of the widest possible range of colour designs, all of which express communal harmony, can help to accommodate individual preferences. This project uses computation to apply colour harmony rules within a chosen environment and to generate all the possible colour combinations which conform to these rules. The Colour Combinations program uses two steps to establish a colour design: palette selection and colour combination. The harmony rules can be adjusted for each step depending on the context for the design or the type of colour combination required. Once an appropriate palette has been selected all possible colour combinations for a terrace of six houses are generated. Each combination is then tested for harmony and the number of combinations which conform to the specified rules is displayed. Each harmonious combination can then be displayed in turn for manual selection. The program allows the effects of adjusted harmony rules to be tested and examined quickly. This could allow individual colour preferences to be accommodated within a communal colour design. Keywords. Colour; harmony; facade design. Communal colour designs highlight the conflict between individual colour preference and the community desire for harmony – often expressed as a fixed colour design by an individual designer. The manual design of colour schemes for communal facades can mean that incorporating and adapting to individual preferences is a frustrating and tedious task. Providing the widest possible range of colour designs, all of which express communal harmony, can help with accommodating individual preferences.
- an extreme example where a housing estate due for demolition was hired to film an advert for the Sony Bravia television The geometry of colour systems has been used to develop harmonic combinations since the first colour circle was suggested in the 18th century. In the 20th century notable geometric calculations have included Johannes Itten’s colour wheel (1987) and the colour wheel developed by Gloag and Gold for their Colour Coordination Handbook (1978), which was to be used in conjunction with the Building Research Establishment’s architectural paint system. Definitions of harmony have developed from notions of emotional responses where different colours evoke complementary characters, such as those described by Goethe (Matthaei, 1971), through the physical characteristics of light where different colours can be combined to provide white as demonstrated by Helmholtz in 1852 (Wyszecki, 2000). The perceptual nature of colour has led to the broad agreement that harmony implies an unambiguous relationship between colours, as described by Gloag and Gold in the Colour Coordination Handbook (1978). The relationships which Gloag and Gold describe use the Munsell colour system, whose perceptual basis reflects the way we experience colour. They use the geometric relationships for hues developed by Moon and Spencer (1944) and defined as “identity”, “similarity” and “contrast”. The identity relationship describes two colours which we perceive as identical; the similarity relationship describes two colours which we perceive as different but related (e.g. red and orange); and the contrast relationship describes two colours which we perceive as completely different, such as red and green. These relationships can be applied to hues alone alongside variations in lightness and saturation so that, for example, a pink and red can be seen as different versions of an identical colour. Computation is now frequently used to develop and display colour combinations, generally for graphics applications, with sophisticated examples such as Coloroid Professional (www.flexinform.com: May 2007), but sometimes for interior colour schemes, as in the case of Dulux’s Colour Coordinator (www.dulux.co.uk: May 2007). We are unaware of colour harmony calculations which use exterior colour schemes as examples. The complexity of the exterior environment and the changing light level, from the broad spectrum and high light levels of daylight to the narrow yellow and low levels of street-lighting, produce a context with an enormous range of colours. In residential settings the complex and changing preferences of residents must also be considered. These difficulties in producing harmonic combinations for exterior use are balanced against an overt desire for colour in the built environment. The increased availability and quality of exterior paints has led to the development of a new vernacular across Scotland and Ireland (McCarthy, 2000), as towns and villages have developed highly chromatic streetscapes, with Tobermory on the west coast of Scotland an iconic example of this (Figure 1). The complex and chaotic nature of exterior colour has resulted in the continuing use of hand-produced bespoke colour designs, with designers such as JP Lenclos (2004) producing colour designs that are closely linked to selected environmental colours (Figure 2). However, despite careful analysis and design, one can still encounter problems incorporating the desires of existing residents. The individual desires of residents must be incorporated into a harmonic whole. The prototype software Colour Combinations was developed as part of the first author’s undergraduate dissertation to address this challenge for colour facade design.
- The quality and availability of exterior paints has led to a new vernacular use of colour in Ireland and Scotland (McCarthy, 2000). Towns and villages that previously presented monochrome facades have developed into highly chromatic streetscapes A variety of projects across the UK have attempted to develop these highly chromatic streetscapes communally rather than individually – examples of these from the west coast of Scotland are: Tobermory – a planned port town with an icon colour scheme that has been developed individually since the 1950s (and now features as an integral part of a children’s TV series “Balymory” – these image dates from 2000 and the building on the right – the Mishnish Hotel – has now been painted black by the owners. Context Existing colour matching systems or software produce colour combinations of two, three or sometimes four colours, all of which are mutually harmonious. Our software addresses a situation which, whilst not unique to the built environment, occurs frequently in exterior environments. In this situation a large canvas, such as a facade, contains multiple colours and is situated within a larger, uncontrolled, environment. The facade colours should harmonise with the environmental colours and with their adjacent colours, but all the colours do not have to be mutually harmonious. A basic and common example of this is a terrace of houses where the first house colour should harmonise with the second; the second should harmonise with the third, and so on; but the first does not need to harmonise with the third. In this situation the coherence of the whole colour design can be provided in a number of ways: the use of a limited palette, such as in the centre of Turin, where just eight colours are proscribed for use on building exteriors; the use of one type of colour, such as terraced housing in Glasgow, where extremely pale colours are used for building facades; the use of a standard colour for a common building feature, such as on the Venetian island of Burano, where a large variety of colours are used for the building facades but there is a universal use of terracotta roofs and white window surrounds. This software was developed to test the possibility of generating sequential colour combinations for the built environment which acknowledge both environmental colours and the use of common colours for common building features.
- Colourful, contrasting scheme
- From the soil colours Similar hues
- Predefined palettes interiors
- Just showing hues here, but applies to any distance in 3D colour space
- A starting point is the broad agreement that harmony implies a clear-cut unambiguous relationship between colours (Gloag and Gold, 1978) and the attempt by Moon and Spencer (1944) to define these relationships. They proposed a numerical synthesis of colour harmony based on the theories of Chevreul, Goethe, Bezold and Munsell. They explicitly ignored the effects of adaptation of the eye and varying areas of colour and, although they suggested that some harmonies may be better than others, they refrained from attempting to rate them. Their rules are based on a three-dimensional colour space which is cross-referenced to Munsell.
- This project has used computation to apply colour harmony rules within a chosen environment and to generate all the possible colour combinations which conform to these rules. The program uses the colour harmony computation derived by Moon and Spencer (1944) using the Munsell system and based on identical, similar and contrasting combinations as a starting point. For this initial phase of development only harmony amongst different hues was considered although the saturation and lightness of the colours produced can be adjusted within the program. The program uses simplified symbols (blocks and circles) to express key elements of the complex colour environment. The example that was used for the development of this program is a terrace of six houses in the west of Glasgow – typical of many British urban developments in the late twentieth century. To develop and test this software, a terrace in Glasgow was selected (Figure 3). This terrace is typical of many post-war developments in the UK and demonstrates the problem of individual residents contributing to a communal colour scheme. In the existing situation this problem is solved by using pale colours of very low chromatic value which are extremely close to white. The environmental colours were analysed and simplified to two colours which could be used to define the context, and thus establish a colour palette for the design. The predominance of vegetation within the context suggested the definitions of “tree” and “bush” for these colours. A third environmental colour was introduced to acknowledge the use of a common colour across all buildings. In the example selected, the colour of the roofs is common throughout the area, and so the common environmental colour was defined as “roof”. Analysis of external colour schemes also demonstrated that there are often specific colours which are unacceptable for a variety of reasons, and thus two colour ranges can be optionally defined as forbidden for colour selection. .
- Sally mapped the Moon & Spencer rules onto Windows HSL However, Munsell doesn’t map onto HSL
- Light wave frequencies vs. human perception
- For this initial development of the software only harmony between hues was considered. The saturation and lightness of colours can be adjusted on the display but does not alter the harmony calculations. The geometric definition of colour harmony developed by Moon and Spencer (1944) was used as the basis for calculations in the software, although the parameters of the calculation can be adjusted. Moon and Spencer’s harmony was based on the perceptual Munsell colour system (1975), whilst the initial software uses the RGB-based Windows HSL (hue, saturation, lightness) system. These two systems have different geometries (Figure 4), which has produced distortions in the harmony calculations. The display of results of the calculations is diagrammatic and has been used to establish the viability of the calculations, rather than a realistic impression of the colours in context. Calculation The software uses two steps to establish a colour facade design (Figure 5). The parameters used for harmony calculations test generated colour combinations for identity, similarity and contrast. These parameters can be adjusted or, indeed, ignored. The software can use all 256 hues within the HSL system, but this generates an unwieldy number of combinations, so the number of hues can be limited by selecting only every nth hue. Colour Palette The three environmental colours and optional two forbidden colours are selected. The harmony parameters and number of hues are then selected. The software then tests all hues to see if they fulfil the harmony criteria. Those that do are displayed in rotation. This process can be run with different parameters until a suitable palette is selected. Colour Combinations Once the colour palette is selected the environmental and forbidden colours are not used in further calculations. The harmony parameters can be adjusted again—for example, to produce colour combinations with strong contrast but no similarity or identity. The software will generate all possible facade combinations using the selected colour palette, and it will then test each combination using the harmony criteria. The colour combinations which fulfil the criteria will be displayed in rotation. This process can be run with different parameters to test the effect of varying harmonic criteria.
- Calculation The software uses two steps to establish a colour facade design (Figure 5). The parameters used for harmony calculations test generated colour combinations for identity, similarity and contrast. These parameters can be adjusted or, indeed, ignored. The software can use all 256 hues within the HSL system, but this generates an unwieldy number of combinations, so the number of hues can be limited by selecting only every nth hue. Colour Palette The three environmental colours and optional two forbidden colours are selected. The harmony parameters and number of hues are then selected. The software then tests all hues to see if they fulfil the harmony criteria. Those that do are displayed in rotation. This process can be run with different parameters until a suitable palette is selected. Colour Combinations Once the colour palette is selected the environmental and forbidden colours are not used in further calculations. The harmony parameters can be adjusted again—for example, to produce colour combinations with strong contrast but no similarity or identity. The software will generate all possible facade combinations using the selected colour palette, and it will then test each combination using the harmony criteria. The colour combinations which fulfil the criteria will be displayed in rotation. This process can be run with different parameters to test the effect of varying harmonic criteria. Presentation The software presents the facade design in a diagrammatic form with information on the colours selected (described in both RGB and HSL format). As part of the development of the software, the colours selected were mapped onto the terrace that was used for analysis, using Photoshop to test whether the colours were practical and whether a more realistic display would be useful.
- Palette generation: 6 colours produced Tree & bush hue: 90 Roof saturation: 0 Roof hue: 90 Hues to avoid: 50-110, 160-240 Step: 10 Identity: 5 Similarity: 0 Contrast: 50 Combination generation: 504 combinations Saturation increased at façade edge houses Identity: 0 Similarity: 0 Contrast: 30 The resulting colour scheme, although it uses a very broad definition of contrast, is colourful and dramatic. The large number of possible combinations generated means that individual preferences by householders could also be incorporated whilst maintaining the effect of contrast and without starting the design from scratch again.
- Palette generation: 8 hues produced Tree & bush hue: 110 Roof saturation: 0 Roof hue: 110 Hues to avoid: 50-240 Step: 7 Identity: 5 Similarity: 30-40 Contrast: 70 Combination generation: 106 combinations Saturations of individual houses changed as in example Values of individual houses changed: darker towards edges of row Identity: 0 Similarity: 20-30 Contrast: 228 The resulting design shows a more muted but still varied design. It also shows an asymmetric contrast between the saturation and values of the first and second house which is emphasised by the inconsistencies of the HSV colour system (where yellow hues are consistently lighter than other hues of the same numeric saturation and value). The application produces combinations based on adjacent colours and does not allow patterns to be specified (although they can be selected from the combinations generated) and, although the saturation and value can be manually specified to produce the subtleties of effects in designs such as Chateau Double, the limitations of transforming hues alone is demonstrated in this example. The palette for this design could be limited further by excluding colours such as the pink on the fourth house and contrast could reduced further by changing the similarity value.
- Palette generation: 8 hues produced Tree & bush hue: 90 Roof saturation: 0 Roof hue: 90 Hues to avoid: 80-150; 180-210 Step: 7 Identity: 5 Similarity: 20-50 Contrast: 100 Combination generation: 42 combinations Saturations of individual houses changed as in example Identity: 0 Similarity: 20-40 The use of greens and purples in the resulting facade is striking and demonstrates the difficulties of using greens on exterior facades, their uniform colour presenting an ambiguous relationship with the surrounding foliage. The use of purples contrasts with the green colours but, as a domestic facade colour, is unexpected. This example demonstrates the importance of selecting or excluding colours for the initial palette which are appropriate to the context.
- Further Development The software has demonstrated the possibility of using computation to test harmonic combinations, and further development is now planned to allow greater use and testing in real design situations. The inputs could be altered to allow more intuitive descriptions and options, such as colour picking from images. The outputs of the calculations could be provided in more realistic and varied views, with information on options such as paint references. The outputs could also be linked to existing visualisation software. Optimisation of the outputs and the display of multiple outputs would also allow easier selection of preferred options. The calculations could be developed to remove harmony distortions due to the different colour systems. The calculations could also be extended to include lightness and saturation as well as hue.
- This application allows the effect of design decisions to be easily viewed and assessed. For a given set of decisions it produces manageable numbers of combinations within which the preferences of a number of individuals could be accommodated. These examples demonstrate the strengths and weaknesses of this application which, by automating the results of design decisions, can generate possibilities that would take far longer manually, but which is still limited by the decisions taken. Further developments of this application could include: allowing colours rather than numbers to be used for inputs producing outputs in a format that allows better assessment of the scheme in context the flexibility to cover a variety of different forms of facade rather than a single example the flexibility to use different elements to establish context or provide unifying colour the ability to fix specific colours within a scheme or to limit specific elements to their own palettes the ability to specify patterns or rhythms within a colour scheme incorporating variation in saturation and value incorporating the relative complexity of the design, involving the form and area of design elements using a more perceptually accurate colour system than HSV This software has demonstrated that calculation can sort harmonic colour combinations from the large number of colour combinations possible on building facades. The complex nature of the exterior environment has been acknowledged but simplified to produce useful results. The software does not replace individual or cultural preferences, but encourages the use of a large range of harmony types and colour combinations. The software is currently a prototype but has demonstrated the possibility for further development and greater use.