This used to work fine with doxygen 1.6.3, but it is broken in 1.7.3:

When using a file like this:
-----------------------------
/**
 * abc
 * @dot
 digraph G
{
  graph[rankdir="TB",bgcolor="transparent"];
  
  Tria -> DoFHandler;
}
 * @enddot
 */
class X
{};
-------------------------------
...then doxygen generates the image file into the correct directory
but the HTML file contains a *global* pathname to it, in my case
like this:

<img src="/home/bangerth/tmp/doxygen/html/inline_dotgraph_1.dot.png" alt="/home/bangerth/tmp/doxygen/html/inline_dotgraph_1.dot" border="0" usemap="#/home/bangerth/tmp/doxygen/html/inline_dotgraph_1.dot.map">
<map name="/home/bangerth/tmp/doxygen/html/inline_dotgraph_1.dot.map" id="/home/bangerth/tmp/doxygen/html/inline_dotgraph_1.dot.map"></map>

This is bad since it doesn't allow you to relocate the built documentation,
for example to the website of the project it documents. Rather, it should
just use the relative name -- which is simple enough since the file ends
up in the same place as the html files. As mentioned, this is what 1.6.3
did.

Best and thanks
 Wolfgang