File talk:Chord diagrams K6 matchings.svg
Low visual contrast
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This excellent diagram suffers from one shortcoming – its low visual contrast, which may make it difficult for sight-impaired users to perceive clearly.
How to test for visual contrast? One way of testing whether an image has enough contrast is to desaturate it, i.e. to render it in gray-scale, then assess, for each pair of colours meant to differ, whether they do indeed differ enough. Creating a histogram or colour reduction, followed by visual inspection of the resultant palette, may help with these comparisons. Also, I believe the World Wide Web Consortium (W3C) has both standards and tools available for making images more accessible to low-vision users.
How to improve this image? The simplest fix might be to replace all yellow line segments by ones coloured by any combination of blue and green, with no red, e.g. a dark cyan, making sure it's not so dark as to be near-black. I'd try pure blue first.
