potrebbe essere un'idea! prova a mettere questo tra <body> </body>

<script language="javascript" type="text/javascript">
<!--
var winheight=100 // Questa l'altezza della finestrella alla partenza.Variala come ti pare...//
var winwidth=100 // Questa la sua larghezza //
var cat=null

step=1;

function catswindows(name,width,height,title)
{
if (!document.layers&&!document.all&&!document.getEle mentById)
{
paramstp="height="+height+",width="+width+",top=6" +
",left=6,scrollbars=no,location=no"+
",directories=no,status=no,menubar=no,toolbar=no,r esizable=no"
cat=window.open("","cat",paramstp);
oldstr="<html><title>"+title+"</title><body background="+name+"</b"+"ody></h"+"tml>";
cat.document.write(oldstr);
if (cat.focus){cat.focus();}
return;
}

LeftPosition=(screen.width)?(screen.width-width)/2:100;
TopPosition=(screen.height)?(screen.height-height)/2:100;

if (document.layers)
{paramstp="height="+height+",width="+width+",top=" +TopPosition+
",left="+LeftPosition+",scrollbars=no,location=no" +
",directories=no,status=no,menubar=no,toolbar=no,r esizable=no"}
else
{paramstp="height="+winheight+",width="+winwidth+" ,top="+TopPosition+
",left="+LeftPosition+",scrollbars=no,location=no" +
",directories=no,status=no,menubar=no,toolbar=no,r esizable=no"}

cat=window.open("","cat",paramstp);

if (document.all) // Nella zona sottostante puoi variare CON ATTENZIONE il carattere,la sua grandezza,colore e messaggio di alert in caso di errore.. Anche il colore della finestrella che sfuma puo' essere variato..//
{
string="<html><title>"+title+"</title><body topmargin=0 leftmargin=0 bgcolor=9933ff>";
string1="<div id=loadintxt style='position:absolute;width:100%;top:45%;text-align:center;visibility:visible;font-family:Verdana;font-size:13px;font-weight:bold'>Immagine in caricamento...</div>";
string2="<div id=errtxt style='position:absolute;width:100%;top:45%;text-align:center;font-family:Verdana;font-size:14px;color:red;font-weight:bold;visibility:hidden'>ERRORE!!! Riprovare prego.</div>";
string3='<s'+'cript>'+'var animColorIndex=0;colorArray=["#FFFFFF","#CCCCCC","#999999","#666666","#333333", "#000000","#333333","#666666","#999999","#CCCC CC"];';
string4='function textLooping(){if(animColorIndex==10)animColorIndex =0;'+
'loadintxt.style.color=colorArray[animColorIndex];animColorIndex++;}animInterval=setInterval("textL ooping()",200);';
string5="function erroccur(){clearInterval(animInterval);loadintxt.s tyle.visibility='hidden';errtxt.style.visibility=' visible';}";
string6="</s"+"cript>";
string7='<s'+'cript language="jav'+'ascript1.2">';
string8='function init(){clearInterval(animInterval);'+
"loadintxt.style.visibility='hidden';"+
'fltr.filters.item(0).Apply();fltr.filters.item(0) .Play();'+
'fltr.style.visibility="visible";}'+'</s'+'cript>';
string9='[img]'+name+'[/img]'+
'</b'+'ody></h'+'tml>';
}

if (document.layers)
{
toppos=height/2-40;
leftpos=width/2-40;
string="<html><title>"+title+"</title><body bgcolor='#000000'><div id=loadintxt style='position:absolute;top:"+toppos+"px;left:"+l eftpos+"px;'></div>"
string1='<s'+'cript>var animColorIndex=0;colorArray=["#FFFFFF","#CCCCCC","#999999","#666666","#333333", "#000000","#333333","#666666","#999999","#CCCC CC"];'
string2='function textLooping(){if(animColorIndex==10)animColorIndex =0;document.loadintxt.document.open();'
string3='document.loadintxt.document.write("<cente r><font size=4 face=Verdana color="+colorArray[animColorIndex]+">Immagine in caricamento...</font></center>");document.loadintxt.document.close();'
string4='animColorIndex++;};animInterval=setInterv al("textLooping()",200);</s'+'cript>'
string5='<s'+'cript language="jav'+'ascript1.2">'
string6="function init(){document.catpic.visibility='show';clearInte rval(animInterval);document.loadintxt.visibility=' hide';};"
string7="function erroccur(){errstr='ERRORE!!! Riprovare prego';alert(errstr);}</s"+"cript>"
string8="<div id=catpic style='position:absolute;left:0px;top:0px;visibili ty:hidden'>"
string9="[img]"+name+"[/img]</div></b"+"ody></h"+"tml>";
}

if (document.getElementById&&!document.all)
{
toppos=height/2-40;
leftpos=width/2-40;
string="<html><title>"+title+"</title><body bgcolor='#000000'><div id=loadintxt style='position:absolute;top:"+toppos+"px;left:"+l eftpos+"px;'></div>"
string1='<s'+'cript>var animColorIndex=0;colorArray=["#FFFFFF","#CCCCCC","#999999","#666666","#333333", "#000000","#333333","#666666","#999999","#CCCC CC"];';
string2='function textLooping(){if(animColorIndex==10)animColorIndex =0;ls="<font size=4 face=Verdana color="+colorArray[animColorIndex]+">Immagine in caricamento...</font>"';
string3='document.getElementById("loadintxt").inne rHTML=ls;'
string4='animColorIndex++;};animInterval=setInterv al("textLooping()",200);</s'+'cript>'
string5='<s'+'cript language="jav'+'ascript1.2">'
string6='function init(){document.getElementById("catpic").style.vis ibility="visible";clearInterval(animInterval);docu ment.getElementById("loadintxt").style.visibility= "hide";}';
string7="function erroccur(){errstr='ERRORE!!! Riprovare prego';alert(errstr);}</s"+"cript>"
string8="<div id=catpic style='position:absolute;left:0px;top:0px;visibili ty:hidden'>";
string9="[img]"+name+"[/img]</div></b"+"ody></h"+"tml>";

x=y=step;
while (x | y)
{
cat.resizeBy (x, y);
if (cat.window.innerWidth >= width) x=0;
if (cat.window.innerHeight >= height) y=0;
}
}

cat.document.writeln(string);
cat.document.writeln(string1);
cat.document.writeln(string2);
cat.document.writeln(string3);
cat.document.writeln(string4);
cat.document.writeln(string5);
cat.document.writeln(string6);
cat.document.writeln(string7);
cat.document.writeln(string8);
cat.document.writeln(string9);

if (document.all)
{
x=y=step;
while (x | y)
{
cat.resizeBy (x, y);
if (cat.document.body.clientWidth >= width) x=0;
if (cat.document.body.clientHeight >= height) y=0;
}
}

if(cat.focus){cat.focus();}
return;
}

function CloseCatWin()
{if(cat!=null && cat.open)cat.close()}

window.onfocus=CloseCatWin;

//-->
</script>


e poi questo dove vuoi che si visualizzi l'immagine..
[img]topolino.jpg[/img]


<form action=" ">
<input TYPE="button" VALUE="Ingrandisci" ONCLICK="catswindows('viola.jpg','640','480','Viol a....'); return false" onfocus="this.blur()">
</form>

prova!