Fix issue with contrast stretching when a grid cell is completely masked out.
Fix issue with contrast stretching when a grid cell is completely masked out.

evenator/marti_common,elliotjo/marti_common,swri-robotics/marti_common,evenator/marti_common,elliotjo/marti_common,elliotjo/marti_common,evenator/marti_common,swri-robotics/marti_common,elliotjo/marti_common,swri-robotics/marti_common,evenator/marti_common,swri-robotics/marti_common