Photoshop
Tutorial
Tutorial #12
Working with Layers
It seems that many photographers struggle to understand Layers, what they are and why they are used, but they are probably the most powerful tool available in image editing. Part of the problem is that in image editing there are many different ways of achieving the same thing and so when you read one book or tutorial it differs from another - even though they reach the same goal in the end.
This tutorial is designed to show a few basic examples of using Layers in Photoshop so that you hopefully will understand the principle of how they work and will then be able to build on that knowledge to carry out more complex editing. Later tutorials on this web-site use Layers and so it is useful to know the basics of how they work.
Show the Layers palette
If you cannot see the Layers palette you need to activate it by choosing 'Windows' -> 'Layers'.
What are Layers?
The original image that you import from your camera opens as the Background image. Imagine that this image is a print lying on the table in front of you.
You lay a sheet of clear glass on top of the print.
You add some text to the glass.
As you look down at the image you see both the original background image together with the added text - but you have not altered your original image - all the text is on the glass. You can go back to the glass and change the text or move the glass sheet and so move the position of the text.
Now add another sheet of glass on top of the first one.
This piece of glass has a slight grey tint to it. If you look down at the image now it seems darker than before because this layer of glass darkens the appearance of both the original background image and the text on the first piece of glass. Even now you can still move the first piece of glass and so reposition the text. If you don't like the darker version you can take the last piece of glass off and throw it away.
If you save the image as a .PSD file the layers are retained so you can go back to it tomorrow, next week, next year.... and reposition the text, remove the text layer, darken the grey tint - in fact any change you want.
So from this simplistic analogy I hope you can see how useful layers are and how layers can interact with each other, particularly if you build up a number of them on the same background image.
So what's the problem?
The main drawback is that layers add a lot to the file size and so also increase processing time. Once you are absolutely confident that there are no further changes to be made you can 'flatten' the layers into one image and so reduce the file size - but then you have lost the ability to return to it for later amendments. Also, when there are a number of layers on the same image it can get confusing - which is why it is so important to name each layer as you create it.
Layer types
There are various types of layers but the four most commonly used are:
Background layerImage LayersText LayersAdjustment LayersWe will investigate each in turn.
Background Layer
As seen above the Background Layer is the initial image opened. All further layers lie on top of this one.
Image Layers
Image layers are, by definition, layers that contain some part of an image - whether directly from the original background image or from an entirely different image altogether.
As an example, the image of a horse grazing under a tree at the New Forest, Hampshire, UK is a little 'washed out'. Let's try darkening the tree a little using the 'burn' tool. We don't know how well it will turn out so we don't want to use the tool directly on the original image.
With the image open (remember - this is called the 'background image'):
Choose 'Layer' -> 'Duplicate Layer'
A box will open prompting you to give your new layer a name. By default it calls it 'Background Copy'. Since this is fairly descriptive we can leave it as that for this exercise. Press OK.
You will see, in the Layers Palette, that there are now two layers that look identical; one called 'Background' and now one called 'Background Copy'.
The layer called 'Background Copy' is highlighted blue which shows that this is the layer in use and so anything done now will only apply to that layer.
We can now select the Burn tool
For this example I have used an large exposure setting of 46% deliberately to emphasize the effect.
Painting over the tree with the Burn tool darkens it - but this has only happened on the 'Background Copy' layer - the original 'Background' layer remains unchanged.
If you click on the 'eye' next to the 'Background Copy' layer you can toggle the layer from being seen so that you just see the original 'Background' layer.
If you don't like the effect on the layer then just click the Trash Can and the layer will be deleted leaving the original 'Background' image intact.
As a further example to show the power of layers, we now use the Quick Selection tool to make a selection of just the horse.
Now we use the 'Layer via Copy' command to create a new layer that just comprises of the horse selection.
Choose 'Layer -> 'New' -> 'Layer via Copy'.
Top Tip !
To create a copy layer of the current selection, just press 'Ctrl-J' on the keyboard.
Now comes the clever bit: With the new layer highlighted blue in the Layers Palette, select the 'Move' tool.
Click and hold on the horse and drag it to a new position. Because it is a copy of the original there will now be two grazing horses in the image.
If you are planning to add more layers now is a good time to re-name your new layer. Double-click on its name in the Layers Palette (at the moment it is just called 'Layer 1'). Type over this with a new name. We will call it 'Copy Horse'.
Text Layers
For photographers the most common reason for adding text to an image is as a title, to add the photographers name or, more commonly, to add a copyright notice. We will now add a title to the Grazing Horse image.
Choose the 'Text' tool and then click-and-drag a rectangle on the image roughly in the position where you want the text. You will see that a new 'text layer' has automatically been created.
Before typing any text go to the toolbar at the top and you can change the text attributes including the font, font size and font colour.
You can now type in your chosen title. Click the big 'tick' when complete.
You will notice that the Text layer automatically renames itself with the first few words of the chosen text.
With the text layer still highlighted blue in the Layer Palette, choose the 'Move' tool, click-and-drag your new title to its preferred position.
Top Tip !
If you have your preferences set to 'snap-to-guides' you may find that the layer will 'snap' into a position that is not quite what you want. To temporarily over-ride 'snap-to-guides' just hold down the Ctrl key whilst using the 'Move' tool.
Just to show the power of layers again, click on the 'Copy Horse' layer in the Layers Palette so that it turns blue.
Choose the 'Move' tool and click-and-drag on the copy of the horse to move it to a new position. You will see that even though the 'Text' layer was added after the 'Copy Horse' layer it remains unchanged.
Adjustment Layers
Adjustment Layers, by definition, make adjustments to all the layers beneath it without making any permanent change to the original background layer. As an example we are now going to add a 'Curves' adjustment layer so that we can make the colour 'pop' a little more.
Choose 'Layer' -> 'New Adjustment Layer' -> 'Curves'
You will see a new layer has been created in the Layers Palette called 'Curves 1'.
Modify the adjustment layer to suit your preference. Here I have created a slight 'S' curve to make the colours 'pop' a little.
As stated above, an adjustment layer affects all layers beneath it. In this example it was fine but it could have been that the adjustment layer made unacceptable adjustments to the 'title' text layer. It is important to try and think about the effect of an adjustment layers on those layers below it and re-position layers as required. To do this just click-and-drag a layer to a new position in the Layers Palette.
The Layers Palette
This is the main toolbox for working with layers because it allows you to choose individual layers, identifies them, shows what type of layer they are and in what order they are in.
The most important sections of the Layers Palette are:
Flattening
Once you have finished editing all of the layers you can 'flatten' them down into one layer. This gives a much smaller file size and can then be saved as a universal file type, i.e. Tiff or Jpeg.
Choose 'Layer' -> 'Flatten Image'
If you think that there is even the remotest chance that you may want to re-edit the image in the future save a copy as a PSD file before flattening. This will preserve all of the layers intact.
So there we have it. This is only a brief introduction to layers but hopefully you will see how powerful and useful they are. Later tutorials use layers in specific ways so read those too so that you have a more detailed understanding of them.
In the next tutorial we will be creating differential focus using Quick Mask and the Lens Blur tool - and also using two Adjustment Layers.
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© John Hallett 2008-2010
