Correcting Tone and Exposure - Beginning Photo Retouching and Restoration Using GIMP - page 59

Figure 3-28. Creating a layer on which to make a gamma adjustment

3. Open the Levels dialog box (Image Menu ➤ Colors ➤ Levels). The histogram

shows the two valleys in the middle area (on either side of the data spike).
The highlighted end of the histogram is a bit shy of data as well (Figure 3-29 ).

Figure 3-29. The two valleys in the mid-range area indicate a lack of some image data