The catch phrase "work smarter, not harder" could have been written about Photoshop adjustment layers. Adjustment layers are a smart tool to use when editing photos—they can save you effort because they don’t permanently alter your image, and they’re editable and removable at any time. Adjustment layers can be used as an alternative to making many of the adjustments you typically make using tools on the Image > Adjustments menu in Photoshop—including levels, brightness and contrast, and hue and saturation adjustments.
When you use an adjustment layer to edit your image you’re making a change that can be permanent or not—the choice is up to you. By contrast, if you make the same adjustment using the regular adjustment tools, the changes are permanent and can’t be undone without winding back all the changes you’ve made since.
By now you’re probably wondering how you can create and work with an adjustment layer. And are simple photo fixes all you can do with them? This article will explain how to create adjustment layers and how to use them to edit your images. You’ll also learn how to use an adjustment layer mask to control the area of the image that an adjustment is applied to and how this area can also be edited at any time.
Creating an Adjustment Layer
To create a new adjustment layer, open an image with only a background layer, choose Layer > New Adjustment Layer, and then choose the type of adjustment to make using it (for example, a Levels adjustment, as shown in Figure 1). Although you can change the settings for the adjustment layer later on, you can’t change the type of adjustment used on that layer.
Figure 1 There are 10 adjustments you can make—the Levels adjustment is selected here.
After you select the adjustment, you can name the layer, if desired. Click OK to continue. Depending on the type of adjustment you have selected, a dialog box will appear that allows you to configure the settings for that adjustment. In the case of a Levels adjustment, the Levels dialog box appears. When you have configured the settings, click OK to apply it to the image.
The new adjustment layer appears in the Layers palette above the background layer (see Figure 2). The adjustment layer has two thumbnails: the Layer thumbnail and the Layer Mask thumbnail. (You’ll learn more about using the mask shortly.) Notice that you can view or hide the adjustment layer’s effect on the image by clicking the eye-shaped icon on the left of the layer thumbnail. If desired, you can remove the adjustment layer by dragging and dropping it on the Delete Layer icon at the foot of the Layers palette.
Figure 2 The new adjustment layer appears in the Layer palette and shows a Layer thumbnail and a Layer Mask thumbnail.
To alter the adjustment settings, double-click the adjustment layer thumbnail to open the appropriate dialog box (in this case, the Levels dialog box). You can now alter the settings you created earlier and click OK to return to editing the image.
An adjustment layer affects all layers below the adjustment layer in the layer stack. If it is positioned between two layers, it affects the one below it, but has no effect on the one above it (see Figure 3).
Figure 3 The adjustment layer affects only the layers below it; it has no effect on the right side of the image, which is on the layer above it.
If you want to limit an adjustment layer’s effect to only one layer, you can do this by creating a clipping grouping. First, ensure that the adjustment layer is positioned immediately above the layer that it should affect. Hold your mouse over the border between the adjustment layer and the layer below it in the Layers palette. If you’re using Photoshop CS2, press Control+Alt+G to create a clipping mask (or Option+Command+G on the Mac). In earlier versions of Photoshop, the command is Control+G (or Command+G on the Mac).
This clipping mask limits the affect of the adjustment layer to the base layer in the clipping group. Because this clipping group is only two layers, it’s the one below the adjustment layer (see Figure 4).
Figure 4 Use a clipping mask to limit the affect of the adjustment layer to the layer at the bottom of the clipping group—here it’s the inset image.
Click the Adjustment Layer thumbnail in the Layers palette and you’ll see that adjustment layers have the same blend modes and opacity settings available to them as other layers in the layer stack.