In general, colour is usually detected by the intensity of the colour itself, its ability to reflect light, or a combination of the two.

Visual impairment affects colour vision in many ways, with some people being unable to see colours very well while others may see colours differently from others using the same space. However, regardless of what colour is actually seen, most visually impaired people are able to detect a contrast between adjacent colours. It is vital to make the most of contrast and lighting design to enhance people’s spatial awareness and help them use their residual vision to navigate buildings.  

When entering a space, most people look around to understand the area they have entered. People with good vision usually do this instantly. Visually impaired people, however, often pause to gather information about the space or adjust to changing luminance. They often first try to discern the visual contrast at the wall/ceiling junction, usually the least cluttered area of a room, to establish a change of surface area or feature. When they start to move, they concentrate their vision downwards, within 2m, and scan the area in front of them for contrasts between features.

Light Reflectance Values (LRVs) indicate the amount of visible and useable light that is reflected off a surface when illuminated by a light source. Colour is a key variant with typically the brightest whites having an LRV of 85 points and the darkest blacks 5 points.