Color correction can do a lot to improve an image. It can reduce, if not eliminate, the color cast that results from indoor film being shot outdoors or vice versa. It can brighten an underexposed image or help to bring out some detail in an overexposed film.
There are limits to what color correction can do.
In spite of what you sometimes see in the movies or on TV, no amount of color correction or image processing is going to make a overexposed, out-of-focus and shakey piece of 50 year old 8mm film look like it was shot last week on an $80,000 broadcast camera by Hollywood cinematographer. Color correction and image processing can make a bad image better, but there are limits. On a scale of 1 to 10 if there is enough information on the film to work with, it might be able to turn a "3" into a "5". Expecting to turn a 3 to a 10 is not realistic.
Press the arrow button in the window below to see some real-world color correction examples.