[TxMt] how to set paths for Textmate.exit_show_html ?

[Piero D'Ancona]

I have an html file containing
     <img src="dvipsnames.png"/>

The image renders correctly in the browser and also
in TextMate's builtin preview.

However, if I pipe the same file to Textmate.exit_show_html
the image does not show.

How should I specify the path to the picture so that
Textmate.exit_show_html can find it?

Thanks
Piero