Hi color palette fans,
As Ansley has mentioned, Ferret has a lot of centered palettes, most of which include "centered" in their names and others tend to have names like "blue_darkred" . Some of these centered palettes have white or light gray at the center.
Another point I want to make is that you may sometimes want to avoid having two intervals both assigned white. Suppose your contour levels are . . . , −4, −2, 0, 2, 4, . . . Then, you often end up with having both intervals [−2, 0] and [0, 2] assigned white or gray. That looks a bit awkward in the color bar and you feel you are wasting color resolution. In such a case, you might want to set your contour levels to . . . , −5, −3, −1, 1, 3, 5, . . .
Regards,
Ryo