What is a Layer ?
A layer works like a piece of acetate placed over your picture....that's it really. Whatever you do on that layer will sit on top of the layers below, delete the layer and everything on it goes but the other layers are unaffected.
For example, open up a picture in Photoshop then take a look at the layers palette:
Your picture has come in to Photoshop as a layer called "background", this is a special layer that is locked. We will get round to how to unlock it later, but for the moment believe me when I say the padlock to the right means its locked. now we will add a new layer on top of this.
Adding a new layer
Click the new layer icon at the bottom of the pallet
and a new layer is added to the document. Because this is transparent (like clear acetate) you won't see any change to your document except that the layers pallet now looks like this:
So we have a new layer, layer 1, the fact that it is highlighted tells us this is the active layer so that anything we now do will only affect this layer, and the eye symbol tells us it's visible. Now take a brush tool and paint all over the image with it:
Now that's pretty - "but what's the use in that?", I hear you ask. Well if you click on the eye symbol next to layer 1 you can switch this off and on. So at any time you can see what the picture looks like with & without your changes.
A popular use for this would be when cloning out an element in the picture. First add a new layer then select the cloning tool and make sure sample all layers is selected. Now all the cloning is on this new layer and doesn't affect the background layers at all. Should you decide that the cloning doesn't work you simply drag it to the new layer to the bin at the bottom of the page.
If you save the image in Photoshop (psd) or tiff format your layers will be preserved for use next time you open the file.
Working with the Background Layer
The only thing that is special about the background layer is that it is locked. This means that we can't add layer effects, or change layer order and a whole host of other things. In order to unlock it simply double click on the little lock symbol. A dialogue box appears:
If you click OK you end up with the background layer renamed to layer 0, now it is exactly the same as any other layers in the document.
To change a layer into the background layer either:
- Select Layer > Flatten Image, which will condense all the layers into the background.
- Select the layer you want as a background and chose Layer>New>Background From Layer.
Deleting a Layer
To delete a layer simply highlight it in the layers pallet then either:
- Right click and select Delete Layer.
- Drag it to the little bin icon at the bottom of the layers palette.
Next time we'll look at using layers to create a simple border effect.