Does your access map have the right colours?

A woman holds a tablet with a map on the screen, She is standing in the street. Does your access map have the right colours?
A digital map

Being able to find places easily is key to getting out and about at any age or level of capability. Online maps are becoming more sophisticated with interactive content and different layers of information. Graphics and colour are used to emphasise places and attributes. But not everyone can see certain colours. So, does your access map have the right colours?

The number of people with colour vision deficiency (CVD) is growing as some people acquire it as they get older. Map Design for the Color Vision Deficient provides a background to this issue and tools for selecting the colours when designing maps. You will need institutional access for a free read. A similar paper is available on ResearchGate.

From the abstract

The golden rule of map design states that one should carefully consider both a map’s purpose and its audience. Maps designed for the general public frequently fail to consider the portion of our population with color vision impairment or color vision deficiency (CVD), known more commonly as color blindness. Recent studies indicate that over 5% of our Caucasian male population are susceptible to congenital or inherited color vision deficiency.

CVD also can be acquired from chemical exposure, injury, illness, medication, and aging. With the exception of aging, little or no data exists on the number of people impaired by any of these non-congenital causes. Recent research has revealed that as many as 20% of those studied over the age of 72 suffer from a blue-yellow defect that increases with age to nearly 50% at age 90.

This acquired blue-yellow defect also is the predominant CVD for those suffering from chemical exposure. This chapter examines the effects of CVD and attempts to illustrate the impact of color choices on visually impaired audiences. It shows that the acquired CVD population is growing and suggests colors and alternatives in map design to minimize that impact. 

Maps in shades of grey: is that what you want?

A wheel of all the colours of the rainbowMap design usually relies on colour to convey information. But what if you can’t see all the colours?  You get maps in shades of grey.  Directional maps, such as street maps for example, use colour to indicate train stations and heritage sites. Geographical maps use colour to show height of land, temperature, and to separate land from water. And it’s not just maps – websites suffer the same issues.

Many of these are age-old conventions that designers follow. So how do you know what colours are best to use? The Colblinder website give examples of what geographic maps look like to people with CVD. It also has links to other references and a colour blindness simulation tool. Although this is about maps, it can also apply to websites and printed documents, such as guidelines, and manuals where pictures and graphics are used to inform and instruct.

For research on this topic Anne Kristin Kvitle’s article is worth a read. The article is titled, “Accessible maps for the color vision deficient observers: past and present knowledge and future possibilities”. 

From the abstract

Color is part of the visual variables in map, serving an aesthetic part and as a guide of attention. Impaired color vision affects the ability to distinguish colors, which makes the task of decoding the map colors difficult.

Map reading is reported as a challenging task, especially when the size of stimuli is small. The aim of this study is to review existing methods for map design for color vision deficient users. The study identified two main approaches: pre-processing by using accessible colors and post-processing by using enhancement methods. Some of the methods may be applied for maps, but requires tailoring of test images according to map types.

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