There are various layer options, available through the "Layers" dialog or, if not there, the Layers menu. These options show some of the most powerful features of layers.
(The example "Layers" dialog shows an image of a house on the Background Layer - see Background layer - and a Super Nova filter on Layer 2. The images can be combined in the image window to show a house with a super nova filter, or either layer can be switched off to show only the image on the other layer. The active layer in the example is Layer 2 and all actions will take place on this layer until the other one is selected.)
We will go through the options in the "Layers" dialog not already dealt with in Creating and working with layers. After that we will cover some of the options available through the Layers menu.
Click on the New Layer button in the "Layers" dialog to open up the "New Layer" dialog.
In the Name box the layer is given a default name e.g. Layer_3. You can change the name as you wish. (The Opacity, Group with previous and Mode options are dealt with in the account of the "Layer Properties" dialog later on in this section.) Click on OK to close the dialog and create the new layer.
Note that whenever you create a new layer it is placed directly above the current highest layer in the stack, that is it becomes the layer furthest from the background. This can be observed in the "Layers" dialog.
If you want to delete a layer, first select the layer in the "Layers" dialog and then click on the Delete Layer button.
You can duplicate a layer by first selecting the correct layer in the "Layers" dialog and then clicking on the Duplicate Layer button.
In the "Duplicate Layer" dialog the layer to duplicated will be given a default name which you can change as you wish. In the Destination box you can choose whether to have the duplicate layer saved to the present document, an already existing document or to a new document.
There are several buttons that enable you to alter the order of the layers. In each case, first select the layer to be moved.
Click on Layer Up to move a layer one up the stack, that is one layer further away from the background.
Click on Layer Down to move a layer one down the stack.
The Layer First button takes the selected layer to the top of the stack, that is the furthest away from the background.
The Layer Last button takes the selected layer to the bottom of the stack, that is makes it the background layer.
Click on the Layer Options button to open up the "Layer Properties" dialog.
There are several options here which are also available in the "Layers" dialog itself, such as power to change the name, alter the opacity, and select a different blend mode for the layer. In addition, you can choose to group layers together.
Opacity: use the slider to reduce the opacity of the active layer. In effect, 100% opacity on a layer prevents you seeing through an image to the layer below. As you gradually reduce the opacity the image fades more and more. Note that altering the opacity merely changes the appearance of a layer, but does not effect a permanent change unless you choose to merge or flatten an image (see Merge operations with layers).
Mode: the blend mode determines how colors on the active layer will blend or combine with colors on the layers below (see Blending between layers for more information).
Grouping: The Group with previous checkbox should be switched on if you want to "clip" the active layer to the layer below. Essentially, grouping causes the information on one layer to mask the information on the other. So, if you have two adjacent layers, with the upper layer clipped to the lower, the only part of any image on the lower layer that will "show through" is that which coincides with the image on the upper layer. The image on the upper layer will be seen as if filled with the colors from the image on the lower. Another way of thinking about this is to see the transparent areas of the upper layer as masking the equivalent areas of the lower layer. An example of the use of the technique is when you have some text on the upper layer, say "Happy Birthday", which you want to be displayed with the colors that are directly underneath in the lower layer. You can cancel a grouping by clicking on the checkbox again or by selecting Ungroup from the Layers menu.
Click on OK to close the dialog and apply the changes.
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