The blur filter put over the game when you've been hit/you're drowsy (don't really know what causes it) can be reset by going into the menu and clicking on video settings then exiting again.
This obviously happens as the engine lets you preview graphics settings on the fly so it needs to remove any kind of alteration for you to do so. What it's not doing is either: saving the state of what the vision is like before going into the video settings; or not reloading that state after video settings have been tweaked by the user. {F28224} {F28225} {F28226}