Consequences of grid resampling
-------------------------------

Except for Cartesian cases, we need to resample your geographic grid onto
an equidistant projected grid. In doing so various algorithms come into play
that projects data from one lattice to another while avoiding anti-aliasing,
leading to possible distortions.
One expected effect of resampling with splines is the tendency for the new
resampled grid to slightly exceed the global min/max limits of the original
grid.  If this is coupled with tight CPT limits you may find that some
map areas may show up with fore- or background color due to the resampling.
In that case you have two options: (1) Modify your CPT to fit the resampled
extrema (reported with **-V**) or (2) Impose clipping of resampled values
so they do not exceed the input min/max values (add **+c** to your **-n**
option).