Lightening using gamma correction. We are going to avoid using the Brightness and Contrast commands to lighten our photo, as they risk "blinding" the highlights and "blocking" the shadows. It is better to modify another component: the Gamma curve.

In photography, the sensitometric curve of a film or a photographic paper is defined by the gamma curve, that is to say, positioning the greys between the black, at the bottom of the curve, and the white, at the top. The notion of gamma curve is slightly different in computer graphics, as it adjusts the overall brightness of the screen.