how to get image at design time for a custom control

Hi to all, Usually, design time appearance for a custom control is governed with the help of overriding GetDesignTimeHtml() method.But we get html at design time.Can any one tell me,for a custom control how to get image at design time.I want to display some image at disign time for a custom control. Please, tell me the idea atleast!! Regards, Rajeev