Layers are a fundamental concept in Paint Shop Pro and other first-class graphics programs like PhotoShop. Think of layers as being like transparent sheets of acetate plastic - one layer may contain an image while at the same time having transparent areas that allow underlying layers to show through. Not only can each layer have transparent parts but the overall transparency of each layer can be adjusted as well. Use layers to add elements to your images, create artistic effects and illustrations, and make editing images easier. You can add or delete layers, rearrange their stacking order (the order from top to bottom), and blend their pixels in a variety of ways. Unless you merge the layers, each one remains independent; you can edit it without affecting the others.

For most simple image retouches and corrections, you do not have to add any layers. However, it's generally a good habit to simply duplicate the layer (by choosing Duplicate Layer in the Layers menu) before applying actions such as the photo correction commands. By applying any changes to the duplicated layer, you'll always preserve the original image on its own layer. And when you intend to do more complex work such as add elements to the image, create photo compositions, add text and other effects, etc., it's highly recommended that you utilise layers for these tasks.

The key to working with layers is to use the Layers menu and the Layers palette. The Layers menu can be obtained either in the menu bar or by right-clicking the main part of the Layers palette. If the Layers palette is not visible you can display it with View > Palettes > Layers or just press F8. The layer palette looks something like this:

When you import a photographic image into Paint Shop Pro, the image has a single layer labelled Background. This is a special type of layer which is always opaque (not at all transparent) and which can never be on top of any other layer. However the special 'Background' layer can be made into a normal or 'full' layer at any time by choosing Layers > Promote Background Layer. This will cause the layer to be renamed 'Raster 1'.

Note: A raster image is made up of tiny squares called pixels whereas a vector image is made up of shapes (rectangles, curves etc) created from mathematical formulas. The advantage of vector images is that they can be scaled (stretched) with no loss of quality. There are icons in the layers palette for making new, empty raster or vector layers but usually you won't need these because you can create a new layer containing the image or selection in the clipboard memory just by pressing Ctrl-L or choosing Edit > Paste > Paste as New Layer.

Another type of 'layer' you may see in the layer palette is the 'floating selection' - you would get this if you were to move a selection using a selection tool. A floating selection is not a real layer and will be absorbed back into the layer that it floats on as soon as the selection is deselected UNLESS you promote the floating selection to full layer status by pressing Ctrl-Shift-P.

The eye symbol in each layer indicates that the layer is currently visible - click an eye icon to hide the corresponding layer. The layer whose label has a blue background is the active layer - any changes will apply to that layer only. Click the name of an inactive layer to designate it as the active layer. It's very important to always be aware which layer is active - things will often go wrong for you if you do not pay attention to this!

You can duplicate a layer by right-clicking its name and choosing Duplicate . You can delete a layer by clicking its name and then clicking the delete layer icon just above or by right-clicking its name and choosing Delete.

To change the order of layers simply drag the layers' names into the desired position within the layers palette (except that, as stated above, the special 'background' layer must remain at the bottom of the stack unless it is promoted into a normal 'full' layer).

For more help with layers, use the Paint Shop Pro help system (Help > Help Topics > Contents > Using Layers)

Do you remember working on a photo of the sphinx in front of the Luxor Casino in Las Vegas? Let's use our new knowledge of layers to give the photo a more dramatic sky. The basic idea is that we will put the new sky image into a layer underneath the layer containing the sphinx image, then simply remove the sky from the sphinx image layer to expose the more dramatic sky underneath. Here is the original photo again - copy it and paste it into Paint Shop Pro.

Now copy the photograph below and, in Paint Shop Pro, paste it into a new layer of the sphinx image with Edit > Paste > Paste as New Layer or just Ctrl-L (not Ctrl-V). I photographed this unusual cloud formation from Mougins in southern France and made it more sinister by increasing the contrast in Paint Shop Pro - I am giving you this photo in high resolution so that you can decide which part of the sky you want to use.

The sky image is completely obscuring the sphinx at the moment because the opacity of the sky layer is 100% - try temporarily reducing the opacity level to see the sphinx show through, and then set the opacity back to 100%. To adjust the opacity of any layer (except the background layer) slide the corresponding opacity slider in the layers palette.

Now we would like to move the sphinx layer on top of the sky layer - try dragging the sphinx layer up or the sky layer down in the layer palette. It's impossible! This is because the background image is not a normal or 'full' layer just yet - it's a 'background layer which has restrictions such as being locked into the lowest level of the stack. Convert the background layer into a normal layer by right-clicking its name in the layers palette and and choosing Promote Background Layer. Now that the background has been promoted to full layer status you can drag it above the sky layer.

Now make sure the sphinx layer is active by clicking its name and then use the magic wand tool to select the whole sky just as you did in the magic wand lesson. Once the sky around the sphinx has been selected, delete it by pressing the Delete key on the keyboard. This part of the image is now transparent, and lets us see the underlying layer, the alternate sky.

Deselect the selected area with Ctrl-D and boost the brightness of the sphinx using the gamma correction adjustment or the curves adjustment. You needn't worry about affecting the sky image in the other layer because only the active layer, the 'sphinx layer' is affected by your changes.

Does that palm tree in the sphinx's 'elbow' bother you? If you'd like to get rid of it then zoom in a bit (roll the mouse wheel) and then use the eraser tool to remove it. Where the tree is erased, the sky underneath will be revealed, so it should look fine. Alternatively, you could use the freehand selection tool to select the tree, being careful not to select the sphinx. Press delete to delete the selection, then Ctrl-D to deselect the selected area. 

The sky image is much larger than the canvas, so you can only see a part of it - make the sky layer active and then use the move tool to move the sky image around until you get the best effect possible.

Your picture is now finished and ready to save as a jpeg image.

When you are working with layers, try reducing the opacity of some of the upper layers for some interesting effects - this is easy to do using the Layers palette. Note that 'opacity' is simply the opposite of 'transparency' so 'decreasing the opacity' means 'increasing the transparency'.