function activateImage(nb) {

	if(document.getElementById('img_diapo_'+activeImage) && document.getElementById('img_diapo_'+nb)) {
		
	        document.getElementById('img_diapo_'+activeImage).style.display = "none";
	        document.getElementById('img_diapo_'+nb).style.display = "block";
	
	        if(document.getElementById('lien_img_diapo_'+activeImage)) { 
	
	            document.getElementById('lien_img_diapo_'+activeImage).className = "diapo_lien_vu";
	            document.getElementById('lien_img_diapo_'+nb).className = "diapo_lien_on";
	        }
	        
	        activeImage = nb;
	        
	}     
}