With the growth of the World Wide Web and the widespread availability of integrated software development environments and web site design tools, graphical user interfaces are now routinely designed by individuals, either at home or within small businesses. Working independently or in small businesses with limited staffing, these developers frequently have no colour design expertise, either personally or available in-house.
When it comes to selecting a colour scheme, they most often use the default colours or attempt to create a colour scheme themselves. Possible reasons for this include: the importance of the colour scheme is underestimated; contracting out the graphic design is time-consuming and expensive; and lastly, the independent and creative nature of software developers means that they can be loath to admit that they cannot create a scheme themselves: “you just open the colour selector and select a new colour for each item; how hard can it be?”
While developers may be competent at writing software or providing the function- ality behind websites, their technical skills may not include the ability to colour their interfaces well. This can lead to frustration as, even after many iterations, their at- tempts can still be unsatisfactory. Such developers can be technically sophisticated but artistically na¨ıve. They are capable of recognising a colour scheme that appeals, but
are not necessarily capable of creating such a scheme, as MacIntyre (1991) succinctly states: “typical users make far better critics than designers”.
A personal motivation
To provide the perspective of an experienced software developer who was na¨ıve about colour, I will relate my own experience when first designing a web site.
Creating the structure for the site itself was straightforward, but choosing a colour scheme was much more difficult than anticipated. Being reluctant to simply copy the scheme of an existing site, I tried to create a colour scheme myself. The schemes were garish and amateurish, even to one with little design expertise. When continued modifications did not seem to help, I turned to books on art and graphic design. The chapters on colour harmony described various methods of selecting complementary and split-complementary colours using a colour wheel. Puzzlingly, when the colours chosen using these methods were applied to the site, the result was just as garish and looked just as bad (although in a different way) as my initial uninformed attempts.
Evidently, either the guidelines were incorrect (which seemed improbable as they had been written by successful artists who presumably knew what they were talking about), or I was applying them incorrectly. While this seemed more likely, it was diffi- cult to understand how such simple guidelines – along the lines of “use complementary colours, those opposite on a colour wheel” – could be misinterpreted.
Having followed the guidelines, I was perplexed. Eventually, I found my error, which was related to my not understanding the balancing of colour strength against area, concepts that will be introduced in the next chapter. I did not understand – and the books did not tell me – that colour wheels are typically printed with only the fullest intensity (or saturation) colours that the printing process is capable of producing, and harmonious colour schemes generally involve subtler, less intense versions of these colours, particularly when the areas to be coloured are large. Attempting to apply this insight has resulted in this thesis.
My experience encapsulates the problem. Colour design appears deceptively easy. For those without intuitive ability, it isn’t. Without appropriate guidance, it is possible to waste a large amount of time and still only achieve mediocre results. One of the aims of this thesis is a system that could help improve the quality of the resulting colour schemes without requiring a significant time investment.
1.1.1 Colour selection for computer interfaces is important
Before considering why developers may find colour scheme creation difficult, it is nec- essary to show that the colour scheme of a user interface is sufficiently important to justify spending time improving its appearance.
Colour is highly valued as a means of personal expression. The huge range of colour schemes for clothing, interior design and web interfaces testify to this. We re- act subconsciously to colour (Kobayashi, 1981). It can have both physiological effects and psychological associations. Specific colours can evoke particular feelings. These
associations are particularly important commercially. Changing the colour of an ob- ject’s packaging, or more recently, a web site colouring, can have immediate impact on sales (van Geel, 2006), and the aesthetics can affect the perceived trustworthiness of e-commerce sites (Wang and Emurian, 2005; Karvonen, 2000).
The colouring of an interface also affects its usability. Inappropriate colour choices can make the interface less comfortable to use, especially for prolonged periods, and directly affect the readability of text and visual search times (Hilscher, 2005). For some industries, such as air traffic control and security screening, these factors can have safety implications.
While individual colour preferences are subjective, overall there are trends in the use and associations of colour that appear to transcend this. If this were not the case, it would be impossible to create colour schemes with a mass-market appeal, such as the widely-used white and bright leafy green colour scheme associated with freshness and cleanliness.
Interface colour selection is important. Whether used as a means of personal ex- pression via web logs and personal web sites, commercially for business e-commerce sites, or for computer applications, it affects our experience while using a web site or software package, and our perceptions of its creator.
1.1.2 Colour selection is hard
The number of possible colourings of an interface is extremely large. For c distin- guishable colours andninterface elements there arecnpossible colour schemes, not all distinct. To put this into context, an interface with seven colourable elements and using the now-standard 24 bit colour selector enables a user to choose 16,777,2167 different colour schemes. While the number of possible colour schemes is huge, the number of “good” colour schemes is very much smaller. This has been validated experimentally in this thesis, with the results presented in chapter 5. In an experimental trial where hu- man assessors ranked colour schemes created by randomly choosing interface element colours, on a scale of “terrible” to “excellent”, the average was “terrible”. It would appear that in order to select good colour schemes, a method is necessary.
User interface colour scheme selection really is a difficult problem, both from an absolute perspective (the space is very large with very few pleasing combinations) and from the perspective of a user (the number of possible colour combinations is overwhelming, and the tools usually available for colour selection make choosing colours an error-prone and protracted process).
1.1.3 Colour selection tools are na¨ıve
Most of the colour selectors available in current software are simplistic. They enable the user to select colours individually with no cognizance of their use in the context of a colour scheme. Typically, the colours will be chosen using a modal colour selector in which the final colour being chosen is shown on a small swatch, out of context, and usually selected using a much smaller area than that in which the colour will be seen. The appearance of a region of colour is affected by its size and the colours of
nearby objects and the background (Fairchild, 1998). Therefore, a colour chosen out of context (such as the swatch in the colour selection dialog) will almost certainly look different when applied to an object in the interface. This necessitates invoking the colour selection dialog again, and again, and again.
Advances in desktop computing power and display technology have improved the quality of displayed images, but have not had any impact on the methods used to select colour schemes. The problem of colour selection and its current “piecemeal” approach will not be significantly altered by the advances in technology: faster CPUs and better graphics accelerators will not simplify the selection of good colour schemes using the current one-colour-at-a-time approach.
In applications that are oriented towards visual design, predefined colour schemes as well as individual colour selection may be available. This is a significant improvement over individual colour selection, but the overall approach is limited, with the user trying to find a colour scheme from a small and often fixed sampling of all possible colour schemes. It may also be possible to change the dominant colours used in the scheme. This is preferable to the “out-of-context” selection of individual colours, but there are severe limitations imposed by the inability to significantly vary the nature of the “canned” schemes. A method that treats the colour selection process holistically rather than piecemeal or “selection from the catalogue” is necessary.
It is also worth noting that colour schemes for interfaces may require the consider- ation of factors not necessary in other fields of colour design, such as the incorporation of differing colour preferences related to globalisation, and pragmatic considerations the designer may wish to include. Any method used to create interface colour schemes must be sufficiently flexible to allow for the incorporation of such “soft” factors.