Dull photo, bright photo, dark photo, saturated colors, etc. In images, we usually get these terms. When we capture a photo from a camera or scan it by the scanner and see them on the computer, most of the time we are not satisfied by its color, contrast, or brightness.
So we have lots of options for color correction for our images and mover over we have Camera Raw processing in Photoshop, and by this, you got full control over colors for your raw images.
To learn about the basics of colors go to the Color basic tutorial.