SVG Filter Effects

SVG filter effects are effects applied to Scalable Vector Graphics (SVG) files. SVG is an open-standard XML format for two-dimensional vector graphics as defined by the World Wide Web Consortium (W3C). A filter effect consists of a series of graphics operations that are applied to a given source vector graphic to produce a modified bitmapped result.

Filter effects are defined by filter elements. To apply a filter effect to a graphics element or a container element the 'filter' property is set on a given element. Each 'filter' element contains a set of filter primitives as its children. Each filter primitive performs a single fundamental graphical operation (e.g., a Gaussian blur or a lighting effect) on one or more inputs, producing a graphical result. Because most of the filter primitives represent some form of image processing, in most cases the output from a filter primitive is a single RGBA bitmap image (however, it will be regenerated if a higher resolution is called on).

The original source graphic or the result from a filter primitive can be used as input into one or more other filter primitives. A common application is to use the source graphic multiple times. For example, a simple filter could replace one graphic for two by adding a black copy of the original source graphic but offset to create a drop shadow. In effect, there are now two layers of graphics, both with the same original source graphics.