function popImagen(nombre,ancho,alto) {
	var adj=10;
	var w = screen.width;
	var h = screen.height;
	var byFactor=1;

	if(w<740){
	  var lift=0.90;
	}
	if(w>=740 & w<835){
	  var lift=0.91;
	}
	if(w>=835){
	  var lift=0.93;
	}
	if (ancho>w){	
	  byFactor = w / ancho;			
	  ancho = w;
	  alto = alto * byFactor;
	}
	if (alto>h-adj){
	  byFactor = h / alto;
	  ancho = (ancho * byFactor);
	  alto = h; 
	}
	   
	var scrWidth = w-adj;
	var scrHeight = (h*lift)-adj;

	if (alto>scrHeight){
  	  alto=alto*lift;
	  ancho=ancho*lift;
	}

	var posLeft=0;
	var posTop=0;

  var scrHeightTemp = alto - 0 + 2*0;
	  if (scrHeightTemp < scrHeight) {
		scrHeight = scrHeightTemp;
	  } 
	  var scrWidthTemp = ancho - 0 + 2*0;
	  if (scrWidthTemp < scrWidth) {
		scrWidth = scrWidthTemp;
	  }
	  
	  if (scrHeight<100){scrHeight=100;}
	  if (scrWidth<100){scrWidth=100;}

	  posTop =  ((h-(scrHeight/lift)-adj)/2);
	  posLeft = ((w-(scrWidth)-adj)/2);

	if (alto > (h*lift)-adj || ancho > w-adj){
		alto=alto-adj;
		ancho=ancho-adj;
	}
	posTop = parseInt(posTop);
	posLeft = parseInt(posLeft);		
	scrWidth = parseInt(scrWidth); 
	scrHeight = parseInt(scrHeight);
	
	var agt=navigator.userAgent.toLowerCase();
	if (agt.indexOf("opera") != -1){
	  var args= new Array();
	  args[0]='parent';
	  args[1]=nombre;
	  var i ; document.MM_returnValue = false;
	  for (i=0; i<(args.length-1); i+=2) eval(args[i]+".location='"+args[i+1]+"'");
	} else {
	newWindow = window.open("","newWindow","width="+scrWidth+",height="+scrHeight+",left="+posLeft+",top="+posTop);
	newWindow.document.open();
	newWindow.document.write('<html><title>Classic Engines</title><meta http-equiv="imagetoolbar" content="no"><body leftmargin="0" topmargin="0" marginheight="0" marginwidth="0" bgcolor="#FFFFFF">');  
	newWindow.document.write('<table width='+ancho+' border="0" cellspacing="0" cellpadding="0" height='+scrHeight+'><tr><td>');
	newWindow.document.write('<img src="'+nombre+'" width='+ancho+' height='+alto+'>'); 
	newWindow.document.write('</td></tr></table></html>');
	newWindow.document.close();
	newWindow.focus();
	}
}