if (document.images) {            // Active Images
            
            
            imgProyon = new Image();      
            imgProyon.src = "mapa_2_on.jpg";
            
            imgSinton = new Image();      
            imgSinton.src = "mapa_4_on.jpg";
  			 
  			
 	    imgProyoff = new Image();      
            imgProyoff.src = "mapa_2_off.jpg";
            
            imgSintoff = new Image();      
            imgSintoff.src = "mapa_4_off.jpg";
		
        


        }

// Function to 'activate' images.
function imgOn(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "on.src");
        }
}

// Function to 'deactivate' images.
function imgOff(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "off.src");
        }
}

// Function to 'activate' images.
function imgClick(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "click.src");
        }
}