Colour scheme for LUMIN

[GilesStrong]

Current state

The colour schemes for plots are dictated by PlotSettings objects. When these are not passed by the user, a default PlotSettings is used. This uses: tab10 for categorical colours, RdBu_r for divergent colours, and virdis for sequential colours.

These are colour schemes that exist in matplotlib and give LUMIN plots a kind of generic appearance. Additionally, tab10 is often not sufficient for some plots, leading to colour being repeated, or tab20 being used. I don't particularly like tab20 due to the mixture of hard and pastel colours.

Proposal

New default sequential, divergent, and categorical colour maps are set or created. Perhaps a series of styles/moods could be defined, which would change all three colour schemes to preset maps, e.g. 'spring' would favour greener colour maps, 'autumn' more reds and browns.

Requirements

• Sequential colour maps must be perceptually uniform
• Categorical colour maps must be compatible with most forms of colourblindness (can be tested via browser plugins and programs which simulate different forms of colour blindness)
• Categorical colour maps should ideally work well in grey-scale (e.g. when for printing a paper in black and white), but this isn't essential
• Divergent colour maps must be symmetric
• Ideally the (categorical) colour map(s) should be consistent with the docs colour scheme; the docs and LUMIN logo colours may of course be changed
• Could schemes must be suitable for scientific publications

Resources

• https://picular.co/ allows for searching for colours and hex values
• https://mycolor.space/ generates colour schemes from a starting hex
• https://stripe.com/blog/accessible-color-systems discusses colour schemes, accessibility, and perceptual uniformity
• https://www.colourlovers.com/palettes user submitted palettes