By the way, in that case something like this could be what you need:
Code:
<h2 title="LA LIONNE">
<img alt="" class="frameGraphics" src="../Images/image003.jpg" />
</h2>
Just set the CSS for <h2> to center alignment and so on... Sigil will create the NCX TOC file for you. And you can make Prince do the same for the PDF.