Accessible Excel (implementation guide)

7.6. Contrasts

Graphic information-bearing elements (e.g. lines, neighbouring areas) have a minimum contrast of 3:1 to the background.

What is meant by this?

Graphic information-bearing elements are visual elements that convey information in a document. These include, for example, lines, neighbouring areas and other graphic "aids". If these are used in Excel, they must have a minimum contrast of 3:1 to the background of the document. The minimum contrast refers to the ratio or difference in brightness or colour depth between the two colours in graphic elements and the background.

Why is it important?

For recipients with visual impairments, sufficient contrast between graphic elements and the background can be crucial for recognising them. Insufficient contrast makes it difficult to recognise and can lead to misinterpretation. It is therefore important that graphic elements such as images or buttons have a sufficient minimum contrast.

Sufficient contrast not only makes it easier for recipients with visual impairments to perceive content. Recipients who work in an environment with poor lighting conditions, have a printout in black and white or are watching a presentation via a projector also benefit from a high contrast ratio. Sufficient contrast ensures that the content is clearly recognisable, making it easier to absorb and process information.

How can I implement/check it?

There are various options in Excel for realising a minimum contrast of 3:1:

1. Use high-contrast colours: Select colours that have a high contrast to each other, e.g. black on white or yellow on black.
2. Use the integrated colour schemes: Excel offers a variety of integrated colour schemes that have been specially developed for good readability and contrast. You can find these options by navigating to the menu item "Page layout" and selecting the sub-item "Colours".
3. Check the contrast with an online tool: There are various online tools that can calculate the contrast between two colours and display whether the minimum contrast of 3:1 is achieved. You can use these tools to ensure that the contrast of your colour combinations is sufficient.

However, it is important to note that the minimum contrast of 3:1 is only the absolute minimum value and it is advisable to use a higher contrast, especially if the document is intended for recipients with visual impairments or reading difficulties.

To ensure that the contrast ratio between graphic information-bearing elements and the background is optimal, you can use free online tools or downloadable programmes.