Spotlight
Apply an image filter to a specific image area (default setting) or magnify an image area.
Note
Change the default settings in the DTX Studio Clinic preferences.
Click Diagnose on the menu bar.
Click Spotlight 
.
Hover over the area to apply the filter or to magnify it.
Note
Use the minus and plus keys (or Shift + Plus key when using macOS) to adjust the magnification level.
Right-click to stop the action.