I wish to make a colormap where the distinction between numbers smaller than 0 and numbers greater than 0 is emphasised. So I want to make a colormap that has one sharp transition in the middle and fades to different colours on the edges. How can I do it? In the manual, I only found how to make gradual transitions.
You can declare your own color map, defining two colours for the transition point. Note that you might need to manually set a finer step size using the optional argument in the color map definition, to avoid incorrect colors near the transition point: