Now that the basic types of layers have been defined, the next step is to manage the layers. Since there are a large number of actions that can be taken when managing layers, this topic will take up both this and the next article.
A new layer can be added to an image by choosing Layer/New/Layer or by clicking on the Create a new layer button on the Layers palette (see Figure 1). Figure 2 shows the Layers palette with a new layer added. This layer will be an Empty layer.
Before one or more layers can be worked, the layers need to be selected. This is extremely easy. A single layer (see Figure 3) is selected by clicking on the layer in the Layers palette. Two or more adjacent layers (see Figure 4) are selected by clicking on the first layer, then, clicking on the last layer while holding down the Shift key. All of the layers except the Background layer (see Figure 5) are selected by choosing Select/All Layers. All similar layers, such as all adjustment layers, (see Figure 6), are selected by choosing Select/Similar Layers.
All of the layers are deselected by choosing Select/Deselect Layers or clicking on the gray area below the Background layer.
Layers are deleted by selecting the layers and dragging them to the Delete Layer button (see Figure 7) or by choosing Layer/Delete/Layers.
A layer is hidden (i.e., its effects/contents are removed from the image) by clicking the eye icon on the layer (see Figure 8). The layer is shown again by clicking the eye icon once more. The contents/effects of a single layer are displayed by clicking the eye icon while holding down the Alt key (see Figure 9). The rest of the layers are shown again by Alt clicking the eye icon a second time.
A layer is renamed by double clicking on the layer name (see Figure 10) and typing the new name. Please be aware that renaming the Background layer will change the layer into a regular layer (i.e., it will no longer have the properties of a Background layer).
In order to move a layer, the move tool is selected from the Tools palette (see Figure 11).
To move a layer within an image, the layer is selected and dragged to the new position. As the layer is dragged, a dotted box will show the position of the layer and a dark line across the Layers palette shows where the layer will be positioned when the mouse button is released (see Figure 12).
The contents of a layer can be moved (i.e., shifted) within an image. To do this, all of a layer is selected by choosing Select/All, or part of a layer is selected by using one of the numerous selection methods. Then, the selection can be moved in one of three ways:
Figure 14 shows how a leaf in a layer was selected and moved within the image.
A layer can be rotated (independent of the rest of the image) by selecting the layer and choosing Edit/Transform/Rotate. A box will appear around the image (see Figure 15). Moving the curser to one of the corners of the box will cause a curved, double-headed arrow to appear. Using this arrow to drag the corner of the box will rotate the layer. Double clicking in the image will complete the rotation.
To align layers, select the layers and choose Layer/Align. A menu with six options will appear:
Once the appropriate option is selected, the layers will be aligned. Figure 16 and 17 show an image, with misaligned layers before and after aligning the layers.
Layers can be aligned to a selection. To perform an alignment to a selection, a selection is created. Then, the appropriate layers are selected. Lastly, Layer/Align Layers to Selection is chosen. As in the previous section, a menu with six options will appear:
Once the appropriate option is selected, the layers will be aligned with the selection. Figures 18 and 19 show an image with misaligned objects. The red rectangle was selected and two alignments where used (Vertical Centers and Horizontal Centers).
Layers can be evenly distributed across an image (e.g., the centers of the layers can be evenly distributed). To distribute layers, select the layers and choose Layer/Distribute. The same six options as in the previous two sections will appear:
Once the appropriate option is selected, the layers will be distributed. Figure 20 and 21 show an image before and after distributing the layers (the layers were distributed both with respect to the Vertical Centers and the Horizontal Centers).
Layers can be locked to protect the layer contents. The locking icons at the top of the Layers palette are used to lock the layers (see Figure 22). There are four icons that are available.
Once a layer has been locked, a lock symbol will appear on the layer (see Figure 23).
Layers can be merged. When layers are merged, the merged layers are merged into the Background layer. This reduces the file size. To merge layers, the layers that are to be merged must be visible (the eye icon is on). All layers that are not to be merged must not be visible (the eye icon is off). To merge the visible layers, Layer/Merge Visible is chosen.
Figure 24 shows a Layers palette with two layers not visible. Figure 25 shows the Layers palette after merging the visible layers. As can be seen, the two invisible layers were not affected by the merge.