In this case, it is not actually an image button, it is an image that is a link to the delete page. The link will pass a querystring variable that is the ID oft he record to delete::
<a href="Delete.php?ID=<?php echo(rawurlencode($row_rsname['ID'])); ?>" title="Delete"><img border="0" name="Delete<?php echo(rawurlencode($row_rsname['ID'])); ?>" id="Delete<?php echo(rawurlencode($row_rsname['ID'])); ?>" alt="Delete" src="WA_DataAssist/images/Pacifica/Refined_trash.gif" /></a>