Adjustment Layers: Reasons to Be Cheerful

With adjustment layers the glass is always half full. You'd be crazy not to use them. Especially when you consider that they add almost no weight to the file size. Each adjustment layer is a simple instruction to move a slider, adjust a curve, or change a histogram. Because the adjustments are stored on their own layers, you have total flexibility. You can:

• Double-click the layer thumbnail at any time to revisit the adjustment and see exactly what settings you used.

• Use multiple adjustment layers to get the effect you're after.

• Turn off the adjustment layer to preview the image without the changes.

• Reduce the opacity of an adjustment layer to lessen its effect.

• Change the blend mode of an adjustment layer for a different effect. For example, applying a Curves adjustment for tonal correction sometimes also produces a slight, unwanted color shift. Change the blend mode of the adjustment layer to Luminosity and the color is unaffected; see Figure 5.1.

  Figure 5.1. The original image of these kids is very underexposed (example A). A drastically reshaped curve brings out detail (example B).

  

• Paint the layer mask that comes with the adjustment layer to control what parts of the underlying layer or layers are affected by the changes.

• Create a clipping mask from the adjustment layer to limit its influence to a single layer. Hold down Option/Alt as you choose the adjustment layer from the pop-up menu at the bottom of the Layers palette and check Use Previous Layer to Create Clipping Mask.

• Drag adjustment layers from one image to another.