Michael, Thank you for the most recent version of Heightmap.
It works in MoI5beta as well.
(The pixel width count of the two images that I tried were cut in half.)
Heightmap has a lot of the required code.


Raster gradients can be produced in imagemagick, a free program.
https://imagemagick.org/script/gradient.php
There are numerous versions, including 6 Windows versions and 1 Mac OS version.
De to lack of experience, I am not expressing any opinion expressed about the worth of this program.

- Brian

Does MoI Image command work with image files with 8 or 16 bits-per-pixel,
Static, or dynamic, (Whatever those mean), or HDRI (high dynamic-range imaging)?