Maybe it's because I worked in production for so long, or maybe because the shoot process is just that much more straight forward, but I am way more interested in the post-production part of a film shoot these days. It seems like a mystery, all the things a filmmaker can do in post.
The color correction to a movie (or tv show) is done by a Digital Intermediate Artist, usually known as a DI or a colorist. Their skill set is highly specialized and they work with film after it's been shot and edited. Color correction is one of the final steps in the process.
In the most simplified terms, a DI is responsible for matching up all the tones and colors throughout the movie. So while you have a single scene, it was probably shot with multiple cameras that won't have the exact same light or grain, so the DI goes through and matches it all up, so a viewers eye would never detect an differences in shots. (Except in certain cases where the viewer is meant to differentiate between cameras, like the hidden cameras used in BG.)
A DI is also able to make a blue more blue or a red more red, etc. In the scene I watched them working on, The Gorilla asked for the interior leather of the car to be an exact shade of blue to match other scenes shot at a different time of day. He also asked the colorist to lighten a segment of the screen where the shadows blended in something he wanted to be able to see.
A DI is more of an overview of color for the entire film, and is not the one who would make really specific, photoshop-like changes. In one scene we were watching, I asked what he would do if (for some reason) you wanted every woman in the shot to have the exact same shade of blonde hair. He said that type of work would be done by a flame artist, also a specialized talent, who works on those specific types of changes. A flame artist is almost like a special effects artist in some ways, different from what a DI is doing.
If a movie is supposed to have an overall tone to match mood or time period, this would also be done by the DI. Like if it needed to look like scratchy film or the orange-y tones of the 70's, etc. That wouldn't all be done in post-production (presumably the director would shoot it in a certain way to achieve these effects, too), but a DI would definitely bump up the tone of whatever the filmmaker was going for.
It's tedious work, but so important to the overall look and feel of the movie.
*Since our kids were born, the only thing I have to do with shooting movies is holding the home fort down. But the press and promotions, this is the part I find fun and interesting. We leave next week for the European press tour and I'll be posting as much about this leg of the process as I can. October will be a wild ride!