You need to increase brightness only in the bottom area of the photo, i.e. to correct only a part ot the image.
1. Select the Inner processing area tool from the menu. Draw a line in the bottom part of the photo and drag it to fit the area you need to correct:
2. Choose the Reference White tool and select the region within the defined area:
3. Click the Start button:
You can see this example by running Example 8 from the program menu | Demonstration.