Scanning is a critical stage in color reproduction. It's difficult or impossible to produce high quality results from a poor quality scan.
Software makes it easy to adjust scanners.
But the operator must know which adjustments to make, based on an evaluation of each image that's scanned. Gamma correction affects the reproduction of tones and colors. It affects brightness and contrast in the midtones without changing highlights and shadows. Gamma can be set for each color individually, or for all colors.