Yeah,You are right.
There is a 'Convert to PNG' button in the Jbpm Web Designer.
Using this button, I can get the initial image of my process.
but I can not find the code to achieve it.
Thank you for your help.
http://community.jboss.org/servlet/JiveServlet/downloadImage/2-638799-17374/450-249/%E6%96%B0%E8%A6%8F%E3%83%93%E3%83%83%E3%83%88%E3%83%9E%E3%83%83%E3%83%97+%E3%82%A4%E3%83%A1%E3%83%BC%E3%82%B8+%282%29.jpg
