DOCBOOK-APPS: ignoring images width in HTML

Hi,

I am using in my documents the same image format for both PDF and HTML 
outputs (PNG). Though I want to specify the width for PDF output but not 
for HTML. An option is to define two different imageobject but I find 
much easier to change the XSL template for imageobject and ignore the width.

Can someone tell me the easier way to do so?

Camille.