Adobe Photoshop CS5 for Photographers - Martin Evening [218]
Move tool alignment options
The alignment options are also integrated into the move tool Options bar. To find out more about layer alignment and distribution, refer to pages 514–517.
Layer mask linking
Layer masks and vector masks are linked by default to the layer content and if you move a masked layer or transform the layer content, the mask is adjusted along with it (as long as no selection is active). When the Link button ( ) is visible, you know the layer and layer mask are linked. It can sometimes be desirable to disable the link between the layer mask/vector mask and the layer it is masking. When you do this, movements or transforms can be applied to the layer or layer/vector mask separately. You can tell if the layer, layer mask or vector mask are selected, as a thin black dashed border surrounds the layer, layer mask or vector mask icon.
1.
This photograph contained a clouds layer that had been masked by the outline of the trees. The layer and layer mask are normally linked and here you can see a dashed border surrounding the layer mask, which meant that the layer mask was currently active.
2.
I then clicked on the link icon between the layer and the layer mask, which disabled the link between the mask and the layer. Now, when the layer was selected (note the dashed border around the layer thumbnail) I was able to move the sky layer independently of the layer mask.
Layer locking
The layer locking options can be found at the top of the Layers panel just below the blending mode options. Photoshop layers can be locked in a number of ways. To apply one of the locking criteria listed below, you need to first select a layer and then click on one of the Lock buttons. These have a toggle action, so to remove the locking, just click on the button again.
Lock Transparent Pixels
When Lock Transparent Pixels is switched on (Figure 9.39), any painting or editing you do will be applied to the opaque portions of the layer only. Where the layer is transparent or semi-transparent, the level of layer transparency will be preserved.
Figure 9.39 This shows the Layers panel with a Layer 1 image layer above the Background layer. Lock Transparent Pixels prevents you accidentally painting in the layer's transparent areas.
Lock Image Pixels
The Lock Image Pixels option (Figure 9.40) locks the pixels to prevent them from being edited (with, say, the brush tool or clone stamp). If you attempt to paint or edit a layer that has been locked in this way, you will see a prohibit warning sign. This lock mode does still allow you to move the layer contents though.
Figure 9.40 Lock Image Pixels prevents you accidentally painting on any part of the layer.
Lock Layer Position
The Lock Layer Position option (Figure 9.41) locks the layer position only. This means that while you can edit the layer contents, you won't be able to accidentally knock the layer position with the move tool or apply a Transform command.
Figure 9.41 Lock Layer Position prevents the layer from being moved when you edit it.
Lock All
You can select combinations of Lock Transparent Pixels, Lock Image Pixels, and Lock Layer Position, plus you can also check the Lock All option (Figure 9.42). When this option is selected, the layer position is locked, the contents cannot be edited and the opacity or blend modes cannot be altered. However, the layer can still be moved up or down the layer stack.
Figure 9.42 The Lock All box locks absolutely everything on the layer.
The above options mainly refer to image layers. With non-pixel layers you can only choose to lock the layer position or lock all.
Transform commands
The Image menu provides a choice of options in the Image Rotation submenu to rotate or fl ip an image (Figure 9.43). You can use these commands to fl ip or rotate the whole image 180°, such as when a photo has been scanned upside down.
Figure 9.43 The Image Image Rotation submenu. This menu can be used to rotate or fl ip the entire image.
The Transform commands are all contained in