SASPro layer mask

We have three images:

A sharpened crab      crab m1-seti-hp-2_01
A denoised crab      m1-seti-hp-2_01_duplicate
A crab mask      Mask

 We want the sharp crab on the denoised background. Using the layers module:

•  drop the sharpened on top of the denoised
•  apply the mask to both 
•  invert the mask of the denoised

That's it. BUT... don't forget to Merge the layers, e.g. Merge --> Push to View