About the filters
How to install
To install these filters, copy them into the /Library/Compositions/ folder, creating it if necessary. The filters will appear in Pixelmator the next time it is relaunched, and other applications that load Quartz filters should be able to use these as well.
These filters were created using Quartz Composer, a tool included for free with every Mac, in Apple's developer tools. Quartz Composer is a great application, allowing the creation of visual compositions very easily, while harnessing the graphical power of Quartz itself. While a first approach may be daunting because of the unusual programming method, after learning the basics you can very quickly discover new possibilities, and create interesting compositions with ease.
Draws a drop shadow behind the layer. You can customize the shadow's color, its blur radius, and its horizontal and vertical offsets.
Download the Drop Shadow filter.
Creates an inner shadow or glow. You can tweak the color, the radius, and the vertical and horizontal offsets.
Download the Inner Shadow filter.
Draws a solid colored outline around the image. You can pick the outline's width, color, and sharpness. Additionally, you can tweak the alpha threshold; anything with less opacity won't be taken into account when drawing the outline. However, since the outline is drawn “behind” the image, if a your image has a shadow, it will apply on top of the outline.
Download the Outline filter.
Smoothly fades the edges of your image, using a gaussian blur distribution of alpha. You can choose the fading radius to make the effect stronger or weaker. You can tweak the alpha threshold, to discard parts with too little opacity.
Download the Smooth Edges filter.