First give your image an id. Let assume it's cStatus. The HTML would be:
<img alt="Open" height="16" src="/jira/images/icons/status_open.gif" title="Open - The issue is open and ready for the assignee to start work on it." width="16" id="cStatus">
From then you can access any attribute of the image. For instance to get the value of the title:
This way you can get/change the value of an attribute.