Pseudo layer masks
Before we get into describing the use of true masks in Photoshop Elements, let's have a look at a 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 becomes opaque, therefore blocking whatever effect that particular layer is displaying, to reveal what it looked like before it was changed. For a beginner, this might seem complicated.
Masks are designed to isolate parts of the image in order to make changes without affecting everything in the picture; for example, to change the depth of field "look" in a landscape. To replicate this slightly complex action using a pseudo mask layer (this is my name for the technique), simply duplicate the layer, then add some diffusion (that is, using a Gaussian Blur filter) to the duplicated layer so that everything goes blurry, and then...
