NOOOOOOOOOOOOooooooooo....... ;) This is the exact wrong way round. Continuous colour scales are hugely problematic because of the fact that our colour percept

NOOOOOOOOOOOOooooooooo....... ;) This is the exact wrong way round. Continuous colour scales are hugely problematic because of the fact that our colour perception is closely linked to context. the classic illustration: http://blog.asmartbear.com/wp-content/uploads/Grey_square_optical_illusion.png http://blog.asmartbear.com/wp-content/uploads/Grey_square_op... If precise comparisons are required you're better off not using colour at all. Colour e.g. in choropleth maps, is good for showing broad spatial trends or highlighting particular areas for selection. A bar chart is better for precise comparisons because we're much better at comparing lengths than colours.