Example Concept: Tone curves allow you to adjust the luminance of an image by manipulating a diagonal line on a graph. The bottom-left of the curve represents shadows, the middle section represents midtones, and the top-right represents highlights. By creating control points on the curve, you can drag these points to increase or decrease the brightness of the midtones and highlights. For instance, pulling the midtone point upwards brightens the midtones, while adjusting the highlight point can either increase or decrease the brightness of the highlights, giving you control over the image's contrast and detail.