Photoshop Elements 11 Filter Basics
Selectively apply a filter.
You don’t need to apply filters to an entire image or an entire layer. You can achieve some of the best effects when you apply a filter to only a portion of an image — say, to an object in the foreground, but not on the background.
For example, you can blur a distracting background so that the person in your image gets due attention. Or, as shown, you can apply a Twirl filter to the water, leaving the surfer unfiltered to avoid that overly Photoshopped effect. (Not surprisingly, you find Twirl in the Distort category.)