An Adjustment changes all the color values of the pixels within an image in exactly the same way. A filter is an entirely different thing: it changes the values of the pixels within an image according to the values of its neighbour. For this reason, filters tend to be quite slow to run, compared to Adjustments. Filters are often used to generate textures that are either used directly or passed on via Layer Blends.
An example of some textures made using filters is here (Right click download).
Filters may be used in isolation, but usually they are used as part of a workflow. For example, a Gaussian Blur might be used on a layer which is then set to Overlay blend mode, the result being used to pass a texture onto the layers below. Below is a simple texture made using a sequence of filter edits: :
- The first image is a simple Noise / Noise. This, and the Clouds filter are useful for provide a semi-random 'key' onto which subsequent filters can do their thing.
- The second filter is a Pixelate / Crystalize.
- Then a simple Blur / Gaussian Blur.
- Finally a Sketch / Bas Relief.
The most important Filters keystrokes to remember are:
- Command F to repeat the last filter at the same setting it was last run.
- Command Option F to repeat the last filter via the filter's dialogue box.
Neither of these keystrokes work on the Liquify filter.
Overview of Filters
Though it is tempting to be wildly exited by all the wonderful creative opportunities that the filter menu appears to offer, most of them are not very useful. Here are some exceptions:
Despite its promising name, this sub-menu is full of dross. Avoid, except for...
In digital imaging one is often needing to destroy or erode information. Images might be too sharp, too noisy, too in focus etc. Sometimes they are the opposite (too blurry) but there is almost nothing that can be done about that. Remember: a full-on blur within an image is entirely a photographic phenomenon. Look out of the window and into the distance, does it look blurry? Of course not. The blur was first painted only after the camera was invented (probably by the Italian futurists but most completely by the contemporary paint Gerhard Richter).
Though almost all of these filters might be occasionally useful, I have only covered a few of them as they are easy enough for you to figure out on your own. Start at the Displace filter to get a good overview of what these filters can do and how they work. BTW... many of them were made semi reduntenet when the supper powerful Liquify filter was introduced.
As with blur, noise is one of the 'information destroyers' that we are occasionally obliged to impose or remove upon an image. BTW... if you wish to add realistic photo grain to an image then a far better solution is the Grain filter. However, noise has other uses...
These might occasionally be useful in the generation of textures, especially in conjunction with a Noise filter. However they are easy enough for you to figure out on your own. Fragment can be useful in conjunction with a Gaussian Blur or Box Blur when faking a defocus. Mosaic can be useful when you are trying to down-rez an image, Pointillize and Crystallize are good as preludes to big, distortion textures.
These are where most of PS's authoring filters live (filters that can make stuff from scratch as opposed to editing existing stuff).