Subtitles makes display lighter when on, darker when off

When using iTunes for full screen Movie or TV Show playback, since Mavericks installation (10.9.2), my screen gets lighter when anything appears on-screen (subtitles or the onscreen controller) and then goes back to normal when the subtitle or controller goes off. I'm using a Mac mini (Late 2012) as a HTPC. The latest version of iTunes is installed as is the latest version of Mavericks. This started after Mavericks was installed and was fine in Mountain Lion. It seems to be something to do with the way iTunes displays movies and TV Shows. It doesn't happen in non full-screen. It doesn't happen using VLC as the playback software and it doesn't happen in iTunes for Windows.

This is really annoying because when watching a movie, the screen lightens when a subtitle comes on and darkens back to normal when it goes off, all throughout the movie or TV show. I've taken to leaving the cursor on the on-screen controller and shoving it down to the corner out of sight, but then I have the WHITE circle with the X in the upper left corner burning a hole in my TV screen.

I have searched and searched, but have come up with nothing. Does anyone have ANY ideas??