Learn to love Levels
Master one of the most powerful tools in Photoshop and discover how to correct colours and enhance tones
The Levels command has long been one of the most useful tonal tools on offer in Photoshop. Not only can you use it to lighten or darken an image, you can also correct colour casts, increase contrast, fix exposure, and introduce colour shifts. It’s worth noting that if you shoot in raw, it’s best to make as many tonal edits as you can in Camera Raw before opening the image into Photoshop. But if you need to alter tones once your image is open, Levels offers a fine degree of control.
There are two ways you can apply Levels to your photo: either directly to your pixel layer (Image > Adjustments > Levels, or Cmd/Ctrl+L), or as an Adjustment Layer (Layer > New Adjustment Layer > Levels). The latter gives you more control, as it keeps the adjustment independent from everything else and editable at any time.
Adjustment Layers work by affecting all the layers below them. This means you can build up the effect over several layers: we’ve used separate Levels layers here to correct colours, dodge and burn, and add contrast.