IconMaker

NEWS 12.19.2021. Save Alpha + PostProcess.
Save the postprocess and alpha:

  1. You need to make changes in the project settings Enable Alpha Channel → Allow Though Tonemapper;

Play, and find menu → BackGroundSettings category → Visible → False;

3.In scene delete SkySphere actor.

In output file, you neeed change Min Alpha → 1, Max Alpha → 0

But it is worth bearing in mind that the post-process will be preserved only on the object, and what goes beyond your object will not be preserved.