To make sure your fluorescent images are colour-vision deficient friendly:
- Best practice: Show greyscale images for every individual channel next to a merged image
- Alternative to two-colour images: Green/Magenta, Yellow/Blue, Red/Cyan
- Alternative to three-colour images: Magenta/Yellow/Cyan, Magenta/Green/Blue, Red/Cyan/Yellow
- Alternative to four-colour images: Magenta/Yellow/Green/Blue
Many programs already have built-in tools to help you design accessible figures. Often, grayscale is converted to colour with the use of LookUpTables (LUTs), which couple specific RGB values to grayscale for conversion. Other tools include colour blindness simulators. There is a lot of information to be found for specific programs, by searching for LUTS, palettes, or settings.
A few examples:
- Fiji / ImageJ: LUT Turbo , download the .lut file and add it to your list of LUTs.
- General/Photoshop: Use Adobe Color to check if your colours are safe. Adobe users can save the theme and use them in Photoshop, Illustrator, etc.
- PRISM / Graphpad: Right click on graph > Define color scheme > Colorblind safe
- CARTO: Cartocolors scheme ‘Safe’
- R / R Studio: library(RColorBrewer) followed by display.brewer.all(colorblindFriendly = T)
Check whether your images are colour-vision deficient friendly:
- In ImageJ: Image > Color > Dichromacy or Image > Color > Simulate Color Blindness
- Photoshop: View > Proof Setup > Color Blindness
- Color Oracle: http://colororacle.org/
- Mac / IOS: Settings > Accessibility > Display > Colour filters
Besides using colour blind-safe colours, there are other methods to enhance the readability of your figures in general. Here are a few suggestions:
- Instead of colours you can use patterns, shapes, etc. This has the added advantage that it doesn’t matter if the figures are printed in colour or in grayscale.
- Keep your legend in the same order as your data or directly connect your labels to your data.
- The more colours you use there is less differences between the colours and thus more difficult to differentiate between them. Try to use as few categories as possible.
All images courtesy of Paul Tol, you can find more images on their website