Saving images was limited to 8 bit pixel format which is not suitable for heightmaps. Version 1.6.0 brings you a set of new features for exporting grayscale images and heightmaps. The following are all changes in detail:
* The new node "Save Heightmap" features 16 bit exports of grayscale images (heightmaps). It supports three different file formats.
* The new node "Tiled Heightmap Export" also supports 16 bit data and works similar to the existing "Tiled Export" for 8 bit rgba images.
* Polished all exporting ui widgets for better usability of filename selection.
* Demo Version: Downscaling of images during export now preserves the aspect ratio.
* Several small bugs related to saving and exporting have been fixed.
New Exporting Options (1.6.0 Release)
Source: Steam Community (opens in a new tab)