function captcha_regenerate(thisCaptchaImage) {
	new Ajax.Request('ajax_captcha_regenerate.php', {
		method:'post',
		parameters: {to_call_function: 'captcha_regenerate', captcha_image: thisCaptchaImage}, 
		onSuccess: function(transport){
			document.all('captcha_image').innerHTML = transport.responseText;
		},
		onFailure: function(){ 
			// do nothing;
		}   
	});
}