An Adjustment layer provides you with a non-destructive way of altering your images. You can apply Levels, change the Saturation and even add a Pattern or Gradient Map to images without disturbing pixel information. This gives you the freedom to experiment without risking your image.
One of the most powerful features of Adjustment Layers is the ability to mask in and out any adjustment changes. Because such a method is non-destructive, you can alter or remove the Adjustment Layer any point, providing that the file is saved in .psd or .pdf format.
An Adjustment Layer will only affect the layers beneath it on the layer stack. So if you need to apply it to all layers, place it at the top of the stack.
Creating an Adjustment Layer
To show you one application of Adjustment Layers, I’m going to modify the contrast and light and dark regions of the image below. As you can see, the it is rather flat and totally lacks drama.
- Click on the Adjustment Layer icon at the bottom of the Layers palette.
- Choose ‘Levels’ from the pop-up menu. An extra element should appear above your current active layer (fig.1).
- Within the levels dialogue box, darken the image to the desired amount (fig.2) and click on OK.
- Try hiding/showing your Adjustment Layer. As you can see, the effects of the levels are non-destructive and haven’t really altered anything.
- You can also tweak your current level settings back double clicking on the Adjustment Layer icon within the Adjustment Layer.
- Now, ensuring that the Adjustment Layer is active, paint with the Brush tool, using black as your foreground colour. Black will mask out the applied effects. This is rather like punching a hole through the adjustment layer, revealing the non adjusted data beneath (fig.3).
- You can used multiple Adjustment Layers if you wish, to add different effects onto the image. Repeat the above masking technique to get the best results.