Imaging applications come loaded with capabilities. But what really makes them as powerful as they are is that you can add functionality. Most imaging applications accept filters, plug ins and add ons that can significantly extend capabilities.

The terms filters and plug-ins (and to a lesser degree add-ons) are frequently used interchangeably. They are similar, but not the same. Filters are applets that are used to manipulate images in one way or another. Plug-ins are modules that run within another application, while add-ons generally contain content, such as design templates and clip art. Most filters are plug-ins, but there are some that can be installed as either stand-alone applications or plug-ins, and there are some plug ins, such as output modules, that aren't filters. 

Because Adobe Photoshop dominates digital imaging, Photoshop compatibility has become the standard for filters and plug-ins, but most imaging filters can be used with most image applications. When installed properly, they'll show up in the drop down filter menu of the application being used. (Add-on library content can easily be accessed from within the imaging program being used and easily integrated into any image or composition, but generally isn't actually part of the program.)

There are three broad bases types of filters. There are optimization filters, effects filters and edge filters (which are sometimes grouped with effect filters.) Optimization filters do things like sharpen and blur images; remove electronic noise, dust and scratches; and adjust exposure problems. Effects filters are the largest category. They're used to accomplish just about anything that needs to be done to an electronic photograph, ranging from turning it into a work of art to making it look like it was shot through a frosted window, to making a simulated ceramic mosaic out of it. Edge filters, which are sometimes also referred to as finishing filters, add hairline rules, borders and creative edges.

Creative Photoshop Tile filter

Most imaging applications ship with their own selection of filters. Photoshop, for example, comes with a filter gallery that includes options like artistic filters, distortion filters, sketch filters and texture filters. There are a dozen or so individual filters in each category, and each filter has a selection of three or four controls that make it possible to vary such things as lighting intensity and direction and the degree of effect that will be applied. That's a lot of control. 

Photoshop texturizing filter.

Not all the filters that come with the various imaging applications are the same. Sometimes itís interesting to  use a different imaging application, just because it works with filters differently. Corel Paintshop Pro Photo, for example, has a very functional effects browser that makes it easy to apply any of the more than 30 filter effects. One photo effect filter that I particularly like is the time machine. With one click, itís possible to make an image look like a photograph from a specific time period from the mid 1800's to the mid 1900's, including, if you want, the appropriate border effect. Thatís about as simple as it can get, for instance, to make a simulated Daguerreotype.

Corel PaintShop Pro Photo Daguerrotype Time filter

Corel PaintShop Pro Photo Time filter

Filters that come bundled with these imaging applications are good at what they do, but they're not always the best choice for very complex requirements. Third party filters are frequently more sophisticated and more powerful in handling the tasks that they were designed to do than similar bundled filters.

There are thousands of filters on the market, many of them duplicate what others do, but the variety is actually quite extensive. Some filters and plug-ins are available as free downloads. In many cases, youíll be able to come up with filter that youíll need without having to buy anything. The Plugin Site is one of various sites that include collections of free imaging filters. While there are a lot of free filters, some are quite expensive. Still, if you need those specific capabilities, theyíre well worth the cost. (Something to keep in mind, many of them, even those that cost, are advertised as free downloads. The download and trial period may be free, but continued use of the filter after the trial period or if you want water marks removed, does cost.)

One of the dangers of discovering special effects filters is that they get overused. Often times, the effect hits you over the head, when there should just be a hint of it. Filters can be used to come up with very interesting results, but it's better to err on the side of being too subtle than it is to be too obvious.

The most important filters and plug ins for serious photographers are the optimization filters. And there are a lot of good options out there. Alien Skin Image Doctor has a number of interesting capabilities, including a JPEG repair tool that eliminates (or at least significantly reduces) artifacting. Low resolution JPEG mages are notoriously poor quality. Using Image Doctor on them can save an otherwise marginal image.

Image sharpness is always an issue. Photoshop has its own sharpening routines built in, but there are more sophisticated alternatives available that result in more natural looking images. Of the numerous sharpening plug-ins on the market, one of the most functional is Focus Magic. Besides the expected focusing capabilities, it has a fix motion blur option that corrects the image distortion resulting from taking pictures from moving vehicles. (Sharpening filters are a good example of filter overuse.  It should never be obvious that an image was run through a sharpening filter, yet, it frequently is, even in major national magazines. )

Detail of the eyes of a portrait shot, the original is on the left and the image sharpened in Focus Magic is on the right.

Imagenomic has several plug-ins available, including Noiseware Professional, which makes it possible to selectively remove noise from portions of image. It even includes a texture mimicking option that eliminates that painterly effect in portions of a shot that often results when sensor noise is cleaned up.

Pictographics iCorrect OneClick is an easy plug in to use thatís extremely effective at color correction. It makes it possible to correct and optimize an images color with a single click. It couldn't be simpler. 

There are also an unbelievable number of edge effects and enhancement finishing filters available. With all the different settings and controls, some can apply literally thousands of different edge effects to images, from very stylish looking darkroom type border to silly specialty borders to nice looking frame borders, to finish them off.  I generally use Auto FX Photographic Edges, which can be called up as a plug-in from within Photoshop or run as a stand alone program.

Creative edge effect generated with Auto FX Photographic Edges.

Whether using filters to optimize, manipulate of finish an image, they can have a significant impact on the final image. It's just a matter of finding the right ones for the right image.