Taite wrote:shati makes an amazing point that I think people literally forget when color correcting. Skin tone is the most important thing to pay attention to. Always try to preserve the fleshy tones of skin. Even if you're using a blue color for correcting, you can get away with having a very light blue tone to the skin, and really, you can experiment with this and create different moods, there's no right and wrong. You can achieve a "dreamy" affect with some glow and blue, etc. It's all open for interpretation. But cranking up the saturation, using gradients, or adding a very saturated color at all, I advise being careful because it erases the fleshy tones and then it's so obviously color corrected, but in a bad way. Obviously there's exceptions to this-- it all depends on what effect you want. But this is just something to take special note of.
This this this.
Color correction can work wonders for the mood in a video. As far as the technical aspect of doing this, you want to use something that lets you have control over highlights, mids, and lows, and the RGB for each of those. I forget the name of the one in AE (though I use it all the time >____>) I only use the hue/sat adjustment to desaturate so I can go back in and make adjustments over top of that.
As far as what the colors MEAN, check out color theory and color psychology. Really cool for helping to subliminally influence your audience. Everyone likes to throw grunge on things, desaturate things, and just go nuts with it... "oh hey, instant horror video!" But...
-warm colors, that can literally convey the psychological feeling of warmth, are yellows, oranges, reds
-cool colors, blues, purples, etc, are the opposite
-consider that bright almost unnatural greens and yellows are sickly...poisinous, noxious (just look at poison dart frogs)
-reds and oranges can induce appetite (next time you're at a restaurant, pay attention to the menu layout & colors)
-medium blues make you sleepy (well, at least in theory) and have a calming effect
-the same is true for a medium pink surprisingly
-purple is unsettling as it is not found in nature very often, it is the color of royalty, of rarity (also not surprisingly used as a color for supernatural forces in anime)
You can also work with colors that clash to make your audience feel uneasy. This is the only time I'd recommend using gradients, because you can really wreck a piece of footage Use very contrasty colors to give the effect of "vibration."
Check out Josef Albers, he was an artist that worked in this kinda stuff. (just google image search his name, notice how some of the images might be unsettling, and some seem to shift as you look at them, or even can make some people sick)
So....for example, alternating shots back and forth that are graded with two of these clashing colors will make your audience very uneasy. And it can be subtle, that's what's great about color grading and color psychology. It's like a secret weapon for influencing emotion.