Auto Levels analyzes photos and corrects
common problems in luminance, such as the lack of detail in photos
that were under- or overexposed.
Click the Fix tab to open it.
Select one or more photos in the Photo Browser. (Ctrl-click
photos to select more than one.)
On the Fix tab, click Auto
Levels.
Auto Levels creates copies of the selected photos,
adjusts the luminance levels in the copies, and saves the copies
in the version sets of the photos on which they are based.