By examining the balance of warm and cool, and the presence of primary colors, we can get a good sense of what is going on in an image visually. Mood can be expressed through hue. Each hue is associated with different emotions. Red evokes feelings of strong emotion or anger. Most likely, this association is derived from the feelings we get when we see blood.
Blood red is the ultimate red.
Therefore, in films, red is frequently used for prostitutes, and fast cars. Red suggests extravagance and ostentatiousness. Blue, on the other hand is cool and passive. Therefore, blue is frequently used to stand for truth in blue uniforms and the American flag, for example. Yellow is cheerful, and warm, perhaps like the warm yellow sun.