10.1. How Filters Work

Although SVG is not a bitmap description language, it still lets you use some of these same tools. When an SVG viewer program processes a graphic object, it will render the object to some bitmapped output device; at some point the program will convert the object's description into the appropriate set of pixels that appear on the output device. Now let's say that you use the SVG <filter> element to specify a set of operations that display an object with a blurred shadow offset slightly to the side, and attach that filter to an object:

<filter id="drop-shadow">
   <!-- filter operations go here -->
</filter>

<g id="spring-flower"
    style="filter: url(#drop-shadow);"/>
    <!-- drawing of flower goes here -->
</g>