First – what is a layer mask?
A Photoshop layer mask can be thought of as an invisible mask overlying your image and containing editing information. The mask can be made transparent in some places to allow the background to show through. All this is achieved without actually deleting any information from the image. Layer masks do not take up a great deal of memory and can be removed at any time and the original picture restored. They are saved when you save and close your file.
In Exercise 1 you will learn to combine two photographs using layer masks. In Exercise 2, a second application of layer masks is described.
Exercise 1: Applying and editing a layer mask
1. In PhotoShop, open two different pictures of your own (as in figures 1 & 2). Practice on fairly low resolution images so that you can work more quickly. Position the images on the screen so that you can see both. With the move tool, position the curser in the centre of File 1 and drag it on top of File 2. If you hold down the shift key at the same time, it will be dropped exactly into the middle of file 2. Otherwise, you can move it around once you have placed it there.
2. File 2 should now contain 2 layers (fig 3). You can check this by looking at the layers palate (fig 4). Now close File 1 – it is no longer needed. Your file 2 should look something like figure 3 at this point.