When you transform a layer, you modify the position, scale, shape and even rotation of the layer. Transforming a layer is useful for changing the size or placement of a layer, as well as for adding perspective or distortion. You cannot apply the transformation process to the Background layer; you must convert that layer to a standard layer before you can transform it. To convert the background layer, double-click it in the Layers palette and rename it in the dialog that appears. Alternatively, duplicate the Background layer and transform the copy, leaving the original Background layer untouched. To transform layers, follow these steps:
Choose File, Open and select the file you want to modify.
Choose Window, Layers to open the Layers palette.
In the Layers palette, click the name of the layer you want to transform.
Choose Edit, Free Transform to begin the transformation process. A bounding box with handles at the sides and the corners surrounds the layer or the objects on the layer. To transform just a portion of a layer, select the area before choosing Free Transform so that the bounding box covers only the selected area (see Figure 6.20). Background areas left by the transformation will be transparent, enabling lower layers to show through.
Figure 6.20. Select a layer to transform.
Apply any of the following transformations to the area in the bounding box:
To move the bounding box, place the cursor inside it and drag.
To scale the bounding box, click and drag a handle (use the Shift key to keep the original proportions).
To rotate the bounding box, position the cursor outside it (until the cursor turns into a curved, two-headed arrow) and then drag.
To distort freely, press and hold the key or the Ctrl key and drag a handle. To skew, press and hold -Shift (on the Mac) or Ctrl+Shift (in Windows) and drag a side handle. Press Return or Enter to apply the effect.
You also can apply individual transformation options by choosing Edit, Transform and then choosing the transformation option you want from the submenu that appears. This approach limits the transformation to only the selected task, such as rotating or scaling. In addition, you can transform a layer with numeric precision by choosing Edit, Transform, Free Transform. In the Options bar, you can adjust the Position, Scale, Rotation, and Skew options. This approach is especially valuable when you have to repeat the same transformation across multiple unlinked layers.