One of the reasons I fell in love with movie making (or movie in general) is the fact that it could be something completely complex or straightly simple. The golden rule of movie plot that goes someone-wants-something-and-get-into-other-things-in-between is often dolled up by many forms of storytelling. The storytelling could involve a lot of things, from dialogue to how the scenes are shot, from the wardrobe to how the scenes are cut. And sometimes, Colors.
In one of the most tragic rom-com movie of all time, 500 Days of Summer is not only trying to captivate our heart and ears (the soundtrack are all amazing!), but it also tries to please our eyes with colors. The foreshadowing of the story is brilliantly told by heavy used of colors.