Auto Levels

This command is at Image - Adjustments - Auto Level

The Auto Levels command is similar to Auto Contrast in that it maps the brightest
and darkest parts of the image to white and black.
In the process of mapping the tones (adjusting the contrast) in the Red, Green
and Blue channels, dominant color casts can be neutralized. This is not always the
case; it depends entirely on the make-up of the image. In some cases the reverse
is true; when Auto Levels is put to work on a neutral image a strong cast results.
If this occurs, undo (Edit > Undo) the command and apply the Auto Contrast
feature instead.