- Colour-blind people can't perceive the scale properly
- Divisions between hues produce false visual artefacts
- The order of the hues has no inherent meaning
- Yellow appears much brighter than the other hues
- It is more difficult to see detail than with scales that vary in brightness
NASA has responded to Visual.ly's open letter in the form of Robert Simmon from the Earth Observatory. Robert has been on a similar crusade within NASA to eradicate use of the rainbow colour scale, apparently with some success.
Robert's response has been a series of six blog posts on how to use colour for data visualization. It is the best tutorial I've come across on this subject. The posts are:
- Subtleties of Color
- Subtleties of Color: The “Perfect” Palette
- Subtleties of Color: Different Data, Different Colors
- Subtleties of Color: Connecting Color to Meaning
- Subtleties of Color: Tools and Techniques
- Subtleties of Color: References and Resources
[ 2013-09-24 ] Robert posted this addendum.