Finishing touch achievement in Layers of Fear (2016)

Just to summarize:

Get the wife ending (this was my 3rd ending if that matters)
You wake upstairs in the hallway next to the room full of wife paintings.
Go into the office with the furboy painting and grab the key from on the desk.
Go downstairs and open the only locked door which is the painter's room.
Walk up to the canvas stand with no canvas.
Turn around and look at the window.
Turn back and there will now be a covered canvas.
Pull off the cover.
Achievement