Work out whether palettes are colourblind-friendly

[wurli]

Will require some research.

Will require thought around:

• continuous vs discrete scales (vs spectral?)
• diverging scales
• quantitative vs. qualitative
• See scale_colour_brewer() and scale_colour_fermenter() for details

[cooke-sm]

Just had a chat with the digi team (who are the gatekeepers for publishing accessible content!) and they've made recommendations and suggested some internal resources:

• How to make published materials accessible: https://educationgovuk.sharepoint.com/sites/how-do-i/SitePages/communications-make-your-content-accessible.aspx
• Using colour for communicating is problematic, but anything explained with colour needs to have alt text.
• For colourblind people, sufficient gaps in gradients are required - more information here: https://educationgovuk.sharepoint.com/sites/how-do-i/SitePages/communications-how-to-use-branding-in-the-department-and-its-executive-agencies.aspx

[cjrace]

Just spotted this repo now and thought I'd add that there's guidance and tools for how to do this checking of colour palettes on the bottom of the analysis function guidance on use of colour in data visualisation (as well as other things to consider and cross-government suggested palettes)