October 10 2007
Layers in Adobe Photoshop appear daunting at first; they are powerful and offer a wide range of features, so knowing where to start is a problem. This photography tutorial introduces the basic functions of the icons the Photoshop layer panel as a start towards creating collages and composite images.
Never Edit Original Files
Before you start experimenting with images, make sure you copy your practice images to a separate directory and do not play with the originals. This is the basic principle of digital imaging manipulation, and if you make a mess of the images, as you most certainly will, delete the messy copies and make new copies to continue experimenting.
This technique is adapted from the traditional film darkroom where film strips were stacked in layers in the printing process to form a combined image. In the digital darkroom, separate digital images are similarly stacked as virtual layers to produce the same result. One benefit of using layers is the flexibility it allows for editing and changing your mind.
In our example image there are a number of elements each on separate layers, allowing them to be moved and changed, while the other layers remain untouched.
One way of creating a new layer in an image is via the layer menu system at the top of the main window.
There is also have a new layer icon along the bottom row of the layer panel, it looks like a sheet of paper.
The layer panel indicates the active layer by highlighting the background of the layer name. Mouse clicking on the name of a layer makes it the active layer for editing.
This brings us to the eye on the left hand side of the layer details. If you can see the eye then the associated layer is visible, and is available for editing and shows in any printing or final file save versions.
Mouse click on the eye and it, along with its layer become invisible. However, the layer exists and is ready for use by making it visible.
Like physical layers, the order they are stacked in is important, as a solid object in the top layer will hide anything below it. The chequered area in the layer thumbnail indicates that layer has a transparent background. The layer below is visible except where that layer has content, such as the white bubble layer. This means we can superimpose our collection of objects over the background image and it is still visible, even though it is the bottom layer.
Apart from the basic background layer, the order of layers in the stack is easily changed.
Move the mouse pointer over the layer name in the panel so that you see a pointy finger, then drag the layer above or below other layers.
Saving the composite file as a .psd or .tif in Photoshop retains all the layers as separate entities. Saving as a jpeg in Photoshop automatically combines the visible layers or flattens the image. Keeping the layer structure intact can mean larger files. Photoshop has commands in the layer menu to flatten the file so a master copy can be saved once the processing is finished.
Layers can develop into complex structures and a bit of practical experimenting helps associate the commands with their function.