Solution

The MIG grid (MapInfo Continuous Grid) is primarily used for the MapInfo Professional's Thematic Grids. It is not recommended to use this grid format for gridded data.

Surface grids open in MapInfo Professional with Discover can be modified in two ways, either -

1) Discover>Surfaces>Modify Grid display

2) Map>Modify Thematic Map>Styles

These two methods are only compatible to a limited degree, and some options, such as Sun-shading / Relief-shading are not compatible.

If you open a MIG grid which has been created without Discover, it may appear slightly different.

If you wish to ensure the MIG grid will appear the same without Discover installed, you should use the Modify Thematic option.