All filters do a simple task in a seemingly complicated way. Deep within a filter’s innards is a set of instructions that tells Photoshop Elements 11 what to do with a particular pixel in an image or a selection.

Elements applies these instructions to every pixel in the relevant area by using a process that pixelheads call convolution (creating a form or shape that’s folded or curved in tortuous windings), which normal humans refer to as simply applying a filter.


Corrective and destructive filters

Corrective filters are usually used to fix problems in an image. These filters fine-tune color, add blur, improve sharpness, or remove such nastiness as dust and artifacts. Remember that pixels are still being modified; it’s just that these filters don’t change the basic look of an image. They’re just intended to enhance its good points and hide the bad.

Destructive filters tend to obliterate at least some detail in an original image while they add special effects. They may overlay an image with an interesting texture; move around pixels to create brush strokes; or distort an image with twists, waves, or zigzags. You can often tell at a glance that a destructive filter has been applied to an image: The special effect often looks like nothing that exists in real life.


Single-step and multistep filters

Single-step filters: The easiest filters to use, single-step filters have no options and use no dialog boxes. Just choose the filter from the menu and watch it do its stuff on your image or selection.

Multistep filters: Most filters come complete with at least one dialog box, along with (perhaps) a few lists, buttons, and check boxes. And, almost every multistep filter has sliders you can use to adjust the intensity of an effect. These filters are marked on the menus with an ellipsis (a series of dots) following their names.


Dial down or fade a filter.

Sometimes, you don’t want the full effect of a filter applied to an image. Sometimes, fading a filter a bit softens the effect and makes it look less “digitized.”


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.)