I'm researching subtleties in horror films. For instance, the use of color in The Exorcism of Emily Rose. Or, the leaves (signifying a dream sequence) floating in the hall when Nancy runs out of her classroom in A Nightmare on Elm Street. Basically, I'm trying to learn how certain directors subtly shift moods, perspectives, and even realities. Any suggestions on articles, websites, or books to check out?

Many Thanks,
Christian