Canon PowerShot S120 Manual (en)

Detailed Setting of Image Sharpness
Select [Unsharp mask] from the list box and adjust 
the setting.
Drag the slider left 
or right
Select [Unsharp mask]
Enter a setting (in 
0.1-stop increments)
Adjust image sharpness with the window view set to [400%], [200%] 
or [100%]. If the view is set to [Fit to window] (full view), you may not 
be able to correctly check the adjustment results.