Using Adjustment Layers in Photoshop

An adjustment layer is a special kind of layer used expressly for color correction. What’s great about adjustment layers is that you can apply that color correction without permanently affecting any of your layers. Adjustment layers apply the correction to all the layers below them (in the stacking order in the Layers palette), without affecting any of the layers above them. Because the color correction actually resides on a layer, you can edit, delete, duplicate, merge, or rearrange the adjustment layer at any time. This gives you more flexibility in your image-editing chores and more freedom for experimentation. Photoshop has 12 kinds of adjustment layers, and you can use as many as your heart desires. The adjustments offered are the same adjustments you find on the Image➪Adjustments submenu. Here’s how to create an adjustment layer:

1. Open an image of your choice.
Because you’re applying an adjustment layer, you may want to use an image that is in need of some color correction. In the case of adjustment layers, you don’t need to convert your background into a layer. I chose an image that was way oversaturated.
2. Choose Layer-->New Adjustment Layer. From the submenu, choose your desired adjustment. Name the layer if you want, leave the other options at their defaults, and click OK.
For my example, I chose Hue/Saturation. You can also just click the Create a New Fill or Adjustment Layer icon (the black and white circle icon) at the bottom of the Layers palette and choose an adjustment from the pop-up menu. The dialog box pertaining to your adjustment appears.
3. Make the necessary corrections and click OK.
After you close the dialog box, the adjustment layer appears in the Layers palette. Two thumbnails appear on the adjustment layer. The thumbnail on the left represents the actual adjustment. The thumbnail on the right represents a layer mask. For more on layer masks, check out the “Playing around with layer masks” sidebar. In my example, the layer mask is all white so my adjustment shows up full strength over my image. Like regular layers, you can adjust the opacity, fill, and blend modes of an adjustment layer. If you want to view your image without the adjustment, click the eye icon in the far-left column of the Layers palette to hide the adjustment layer. If you want to delete the adjustment layer, simply drag it to the trash can icon in the Layers palette or choose Delete from the Layer menu or Layers palette options menu.

Editing adjustment layers
After you’ve created an adjustment layer, you can easily edit it. Simply double-click the adjustment layer thumbnail in the Layers palette or choose Layer-->Layer Content Options. In the dialog box that appears, make any edits and then click OK. The only adjustment layer that you cannot edit is the Invert adjustment. It is either totally on or totally off.

To change the content of an adjustment layer, choose Layer-->Change Layer Content and select a different adjustment layer from the submenu. Editing and changing the content works the exact same way for fill layers (which are discussed in an upcoming section).

Isolating your adjustments
If you don’t use an adjustment layer when you make color corrections, the correction you apply affects only the active layer (the layer highlighted in the Layers palette). This may be the way to go if you want to just tweak the color on a single layer. Here are some tips for using and isolating adjustment layers:
- Correct part (but not all) of a layer: To enable the adjustment layer to correct only a portion of a layer, make a selection before you create the adjustment layer. The adjustment affects only the pixels within the selection outline. This is referring to the pixels within the selection outline on each layer that resides below the adjustment layer. In addition to making a selection, you can also create and select a closed path.
- Create a clipping group: When you create a clipping group of the layers you want to adjust, you can place the adjustment layer in or at the bottom of the clipping group, and it will affect only those clipped layers. In a clipping group, the bottommost layer acts as a mask for the layers in the group.
- Create a layer set: You can create a layer set (a grouping of layers) and place the layers you want adjusted in that set. Then make sure that the blend mode is set to any mode except Pass Through.