Before we get into describing the use of true masks in Photoshop Elements, let's have a look at feature I call pseudo layer masks.

A true mask is one that is attached to an image thumbnail in the Layer panel. Its default color is white, which means that it is see-through, but as soon as you paint black onto that mask, it begins to become opaque, therefore blocking whatever effect that particular layer is displaying to reveal what it looked like before it was changed. For a beginner, this is complicated.

Masks are designed to isolate parts of the image in order to make changes without affecting everything else in the picture—for example, to change someone's hair color. To replicate this slightly complex action using a pseudo mask layer (this is my name for the technique), you can simply duplicate a layer, then add a tonal change to that duplicated layer so that the object in the image that you want to enhance looks perfect (ignore the rest of the image while doing this); then, the idea is to erase the rest of that layer to reveal the unchanged original underneath it. The advantage of this technique is that it's basic, and it's very easy to make a significant local change to any part of your picture. Its main disadvantage, I suppose, is that, unlike a true mask, once the pixels have been erased, the process is relatively irreversible so I'd stick to simple edits to begin with.

I might use this technique if I want to increase an out-of-focus look in the background areas without affecting the subject, as if I was reshooting the image using a wider-aperture lens, as shown in the following image.

I would duplicate the layer and then apply additional blurriness using one of Elements' many blur filters (the best one to use is called Filter | Blur | Gaussian Blur), before carefully erasing the subject from this blurry layer to reveal the original, sharp version underneath. This can give you an almost instant shallow depth of field look with very little work on your part. Once done, it's a simple matter of flattening the top layer with the Background Layer before saving it and moving on to the next project:

Making what I call a pseudo layer mask is quite easy. All you need to do is duplicate the layer you want to change—you can clearly see the copied or duplicated layer in blue—in the Layer panel inset. You also need to be reasonably accurate with the Eraser tool, which is tricky at the best of times because the mouse is not exactly an easy-to-control device. Look at the following image:

With the new, duplicated layer selected (active), choose the Gaussian Blur filter from the Filters menu at the top of the screen (Filter | Blur | Gaussian Blur).

The Filter panel pops into the main screen, and you can choose from a tiny bit of fuzziness to all-out blurriness. The idea in this exercise is to make the background of this landscape image appear as if it were shot with a wide aperture—for example, f2.8—rather than at the mid-range setting of f5.6 that was chosen at the time it was exposed. How much fuzziness or Gaussian Blur you add is dependent on the effect you'd like to create and the overall resolution of the original picture. The more megapixels, the more filter effect you have to add to get a good effect. It's easy enough to experiment with duplicated layers. Undo this if it is wrong and try a different blur setting. Look at the following image:

So, having got the blurriness more or less at the right amount, select the Eraser Brush from the Tool Bar. Like every painting, drawing, and selection tool in this program, the brush tip can be varied. Do this by right-clicking inside the main image to access the Brush pop-out menu or going to the Options panel at the bottom of the page.

In this screen grab, note that I have turned the bottom layer Off (by clicking the eye icon next to that layer's thumbnail), so once I begin erasing the blurred layer, it reveals transparent pixels (that's the weird checkerboard pattern seen here) and gives me a better idea of how to be more accurate with my erasing.

To easily regulate the size of the brush tip, you can use the Size slider in the Options panel, but an easier method is to use square brackets. Next to P on the keyboard, press the left [ to make the brush tip smaller and the right-hand ] to enlarge it. This keyboard tip works for all brush-based tools in Elements, Photoshop, and Illustrator.

This is my progress so far. Although I started this technique by stating that this process was easy, I omitted saying that it does take a bit of time, depending on the complexity of the edges of the area being erased, of course. I set the brush opacity to 90% to make the erasing process a bit smoother, but it does take longer to erase all the pixels because you'll have to go over everything twice!

When retouching, you really cannot see smalls detail with the main image fitting the screen—it needs to be enlarged to get into the nooks and crannies. If you take care of the fine detail, then the illusion of a fabricated depth-of-field will appear that much more realistic. Use Ctrl/Cmd + + and Ctrl/Cmd + - to zoom in or out when erasing, respectively. Look at the following image:

Here's another screen grab, full frame, with about 95% of the top layer's pixels removed. It's time to turn the bottom layer back on to get a glimpse of how realistic the fake depth of field effect has turned out.

I could spend a lot more time erasing some of the tiny pixels around these colorful lupins to make everything appear a bit more realistic, but I think 15 minutes was enough to get this to work nicely.

The point of using a duplicated layer is that if you mess up the erasing process, even though it's not always effective to go back to a previous version or change the blurriness, it's easy enough to duplicate the Background Layer again and give it another go.

Note that real layer masking involves a fluid Selection process that can go forward and backward an infinite number of times. You'll find more on layer masking toward the end of this chapter.