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Colour contrast

Whether you’re creating web pages, documents, presentations, or social media posts, colour is an essential part of design. Poor colour choices can create content that is difficult for people with low vision, colour blindness, or contrast sensitivity to see clearly.

While certain colour combinations may be visually pleasing, it is important to understand that low contrast colour choices can be a barrier for anyone with a vision impairment. Good colour contrast can also make your content accessible to anyone who may be in difficult lighting conditions e.g. on a mobile or in direct sunlight.

Web Content Accessibility Guidelines give specific recommendations for minimum colour contrast between text / background colours, and for objects like buttons, icons, and status indicators. 

Colour contrast is the luminance between 2 colours. Luminance can be described as the colour brightness or saturation. Colour contrast is often represented as a ratio: black to white has the highest possible contrast ratio of 21:1. Black text on a white background and white text on a black background has the same ratio of 21:1.

Some people with sensory differences can find documents with 100% white backgrounds hard to read on a screen due to the brightness and glare. It is a good idea to add a soft grey or yellow tint to white to soften the brightness when creating documents that will be read on a screen. Using a subtle 3% tint is often enough.

The lower the contrast ratio, the higher the difficult to read. WCAG recommends not going below 4.5:1 for body text and no lower than 3:1 for heading size text and for non-text
objects like buttons or icons.

It’s important to note that these are minimums. It’s best to aim for a contrast ratio higher than the minimum to ensure readability.

A colour contrast checker is needed to work out the exact colour contrast ratio and whether you are meeting the minimum recommended contrast. You can use an online checker to input
a foreground (or text) colour, and a background colour to get the exact contrast ratio. 

There are different models for describing colour, sometimes referred to as a colour space:

• Digital design requires HEX and RGB colour values.
• HEX values are 6-digit codes assigned to colour and
• RGB values are the percentage of RED, GREEN and BLUE that make up a colour

Print design requires CMYK values. CMYK values are the percentage of CYAN, MAGENTA, YELLOW and BLACK that make up a colour

WebAIM.org has a free colour contrast checker. You can also download a free colour contrast analyser from TPGi.

What do we know?

Providing timely support for children, young people and families is vital. Identifying and addressing a child or family's needs early on can reduce risk factors and increase protective factors in a child's life (Early Intervention Foundation (EIF), 2021). Screening is described as the process of identifying apparently healthy people who may have an increased chance of a disease or condition (UK National Screening Committee, 2023). The screening provider then offers information, further tests and treatment. Some AHPs engage in screening of the population eg newborn screening. Other AHPs may support others in the workforce to screen or identify concerns early so they can be addressed.

How can AHPs contribute to this aspect of public health?

• Provide training/support to wider workforce to identify needs early, or undertake screening
• Develop the use of screening tools/approaches that enhance early identification of needs in the population
• Highlight risk factors which make children more vulnerable to poorer outcomes
• Engage in screening processes where appropriate
• Use opportunities to promote immunisation where appropriate
• Consider adherence to infection prevention and control
• Provide training/support to wider workforce to track progress on children’s developmental outcomes
• Support parents/carers/children in understanding benefits/risks of radiation exposure

Examples:

See4Schools Programme – Orthoptics pre-school vision screening undertaken in NHS Tayside: Fife Loves Life - Dietitians in NHS Fife developed a toolkit and training programme to undertake nutritional screening to support raising the issue of child healthy weight.

Raising Attainment for All – Speech and Language Therapists in NHS Lanarkshire developed checklists to support education staff to identify children requiring support, to monitor progress with speech, language and communication and identify what supports to put in place. Following testing within schools with the highest levels of deprivation, these were then also made available to all primary schools in North Lanarkshire.

Healthy Feet – MSK Podiatrists in NHS Ayrshire & Arran work directly with health visitors and families on early screening, prevention and interventions around MSK foot and ankle health and early gait patterns with a focus on social participation, structure/function, activity / independence and wellbeing.

Health Visitor Training – Physiotherapists in NHS Greater Glasgow and Clyde deliver online sessions for Health Visitors as part of the 13-15 month and 27-30 month pathway in order to provide advice and support on developmental milestones and early intervention and prevention of needs.

Speech, Language and Communication (SLC) resource for Health Visitors – NHS Education for Scotland worked alongside Speech and Language Therapists to develop a SLC supporting resource for Health Visitors to promote early identification of children with speech, language and communication needs and best practice in early intervention at each stage of the Universal Health Visiting Pathway.

Reflection points

1. What aspects of screening do you currently engage with?
2. How do you promote early identification of needs in the wider population you work with?
3. Who are the key partners you could collaborate with?