The **-r** option (grid registration)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

**Syntax**

**-r**\ [**g**\|\ **p**]
    Select **g**\ ridline or **p**\ ixel node registration.

**Description**

All 2-D grids in GMT have their nodes organized in one of two ways, known as :ref:`gridline
<reference/options:Gridline registration>` and :ref:`pixel <reference/options:Pixel registration>` registration. The
GMT default is :ref:`gridline registration <reference/options:Gridline registration>` (**-rg**); programs that allow for
the creation of grids can use the **-r** option (or **-rp**) to select pixel registration instead.

Most observed data tend to be in gridline registration while processed data sometime may be distributed in pixel
registration.  While you may convert between the two registrations this conversion looses the Nyquist frequency and
dampens the other high frequencies. It is best to avoid any registration conversion if you can help it. Planning ahead
may be important. (Node registrations are defined in Section :ref:`option_nodereg` of the GMT Technical Reference.)
