The most common form of colorblindness is deuteranomaly, which is red-green. The colorblindness simulations show the color red as indistinguishable from a certain shade of green.
Actually to my eyes the dichromatic treatment renders both green and red as amber or ochre. Which means that yellow, orange, green, and red are seen as a light yellow to dark yellow spectrum, with purple as a darker form of blue.
This means that the use of red and green as distinguishably different should be avoided. The use of red-yellow distinctions or green-yellow distinctions could work.
Also now that the blue-purple distinction also gets muddled, which is not useful for the dark blue link and purple visited-link color standard in html.
There are three online marketing graphical components which should be made colorblind-safe
- Company logo and other visual brand design elements
- Website color scheme, including background, headers, subheads, links, and visited links
- Any graphical banner advertisements used anywhere on the web
Just like the company or brand name and website URL, which may not be changeable, the company brand colors and logos may be off-limits to optimization. However, any kind of navigation or non-core imagery should be viewed through the lens of the colorblind customer.
Rules of Thumb
Some rules of thumb can be generated from these research findings
- Do not mix green with either red or orange
- Use a darker green against light backgrounds, as light green appears as yellow
- Do not mix blue and purple, and avoid shades of blue to purple, they won't stand out
- Use the VischeckJ tool (below) which will show how differentiated a given logo and graphic scheme is from competitor brand visuals
As per the usual, the idea is to be different, but in a good way.
- ImageJ and VischeckJ
- For colorblind people, the What Color tool helps identify colors on a screen for those who cannot do so visually
- Visicheck has an algorithm called "Dalton" which changes colors to make the distinctions between colors more noticeable for the colorblind
- Visicheck also has online tools to check websites and images