Correct Photos with Uneven Lighting in Photoshop Elements
Examine the histogram.
As a first step in your editing process, open the Levels dialog box by choosing Enhance→Adjust Lighting→Levels. The histogram displays recoverable data; for this photo, most of the data appears on the left and right where the highlights and shadows are. The middle of the histogram shows much less data. Click Cancel in the Levels dialog box when you’re done looking at the data.