[ferret_users] data-adapted centered palette with white always at zero

["'Fabio B.' via _OAR PMEL Ferret Users" <ferret_users@xxxxxxxx>]

Hello,

I often have to plot the delta of different types of variables so often 
with a wide range of values. I would like to plot the positive Delta in 
one color and the negative Delta in an opposite color, and the zero 
value in white. Centered palettes like the centered_diff look nice but 
if the data is not centered around zero the zero might be blue/red and 
it does not serve my purpose. I also cannot edit this palette every time 
the center of the data shifts.

Is there a way have the palette always display white for the 0 value 
regardless of the data range?

Thanks