Imaging Grids With Nans
-----------------------

Be aware that if your input grid contains patches of NaNs, these patches
can become larger as a consequence of the resampling that must take
place with most map projections. Because **grdimage** uses the
PostScript colorimage operator, for most non-linear projections we
must resample your grid onto an equidistant rectangular lattice. If you
find that the NaN areas are not treated adequately, consider (a) use a
linear projection, or (b) use :doc:`grdview` **-Ts** instead.

.. include:: explain_grdresample.rst_

Image formats recognized
------------------------

We automatically recognize image formats via their magic bytes.  For formats
that could contain either an image of a data set (e.g., geotiff) we determine
which case it is and act accordingly.  If your favorite image format is not
automatically detected then please let us know its magic bytes so we can add it.