function deleteUnderscore(Who){
	var newString = '';
	var temp = '';
	for(i=0;i<Who.length;i++){	
		temp = Who.charAt(i);
		if(Who.charAt(i)=='_'){
		temp = ' ';
		}
		newString += temp;
	}
	return newString;
}

function hresimg(img, targeD, Larg, Haut, Gtitre)
{
	var top=10;
	var left=10;
//	var top=(screen.height-Haut)/2;
//	var left=(screen.width-Larg)/2;


  test = '<body leftmargin="0" topmargin="0" marginwidth="0" marginheight="0" bgcolor="#000000" style="cursor:hand" onLoad="resizeTo('+Larg+', '+Haut+')"><script language="javascript">moveTo('+top+','+left+')</script>' + '<img src="'+img+'" alt="Cliquez sur l\'image pour fermer cette fenêtre" onclick="window.close();"></body>';
  
 Grandeur = "width="+ Larg + ",height=" + Haut
 
  toto= open("", targeD,  Grandeur);
  window.toto.document.write("<title>" + deleteUnderscore(Gtitre) + "</title>" + test); 
  toto.focus();

}

<!-- exemple onClick="hresimg(img= 'zoom/img01.gif', targeD= 'zoom1', Larg=500, Haut=365)"-->