We can correct our photographs levels using a few different techniques. The first, being the most obvious, is the auto levels technique. Simply press the "Auto" Button in your levels adjustment, and it will try to calculate the correct levels for your document automatically.

See how much the photograph has improved using this simple adjustment? Take a look at the levels histogram after being corrected:

As you can see, the images tonal range now spreads across the entire histogram rather than just the left side, showing a properly exposed photograph, rather than our previously underexposed image. Sometimes, the auto levels command will not bring out your photograph correctly however. There are a few other techniques that will help in correcting your photographs levels. It is up to you for choosing which one best suits your needs!

Section 5 "Level Points"