Deconvolution

Deconvolution is one of a few multi-step techniques that is part of the standard image processing workflow. 

These videos are more than a simple step-by-step demonstration. They are an in-depth treatment of the topic. One feature of this tool called "Regularization" is covered in PixInsight Horizons (I consider it a more a complex adjustment.) The Deconvolution process' default values in combination with a mask are demonstrated here.