Grading and Coloring are part of the creative workflow that any piece of video goes through (or at least any fully produced piece of video). It controls the overall ‘feel’ of the movie. When I started doing movies in addition to stills this is one of the things that got me on the first few times. It is a very similar concept to using curves, hue/saturation and other tonal and contrast tools on a photograph.
Colorist Rob Bessette of Finish Post gives a great introduction into coloring a video (hosted by Rule Boston Camera). It covers everything from what coloring actually is, through basic principles, setting a monitor up and ends up with a spectacular demo of coloring a commercial. If you are unfamiliar with coloring, you would be surprised at how different a movie looks once a colorist is done with it.
The demos are done on Blackmagic Design’s DaVinci Resolve but similar principles can be applied to more common software like after affects as well.
If you want to see how heavily videos are affected once a colorist is done with them, check out Rob’s demo reel, you’d be shocked.