Generation of Photo Library

<html><head>

<script language="javascript">
function image_rep(x)
{
document.getElementById('imageshow').innerHTML="<img src='images/"+x+"'>";
}

</script>

</head><body>
<div style="clip: rect('top', 'right', 'bottom', 'left'); height:300px; width:300px; overflow:scroll; float:left; text-transform:lowercase;">
<?php
//Open images directory with chmod 0777
$dir = opendir("images");
$dir_image_no=0;
//List files in images directory
while (($file = readdir($dir)) !== false)
{

if ($file != "." && $file != "..")
{
echo "<a href='#' onClick='image_rep(\"".$file."\");'>". $file . "</a><br/>";

$dir_image_no++;
}

}
closedir($dir);
?>
</div>
<div align='left' id="imageshow" style="float:inherit"></div>
<div style="clear:both;"></div>

<div id="photo_lib_upload" >
<?
//code for image upload
if(isset($_POST['subFrm'])&&($_POST['subFrm']="1"))
{
$filename=$_FILES["photo"]["name"];
$ext=explode(".",$filename);
$arrlen=sizeof($ext); //length of array contaning file name

if((strtolower($ext[$arrlen-1])!="php")||(strtolower($ext[$arrlen-1])!="js"))
{
if((strtolower($ext[$arrlen-1])=="jpeg")||(strtolower($ext[$arrlen-1])=="jpg")||(strtolower($ext[$arrlen-1])=="png")||(strtolower($ext[$arrlen-1])=="gif"))
{

$finalname=time().str_replace(" ","_",$_FILES["photo"]["name"]); //echo"filename".$finalname;
move_uploaded_file($_FILES["photo"]["tmp_name"],"images/".$finalname);

$frm_inv="Your image has been uploaded successfully. <a href=# onclick='window.open(\"images/".$finalname."\",\"\",\"height=200,width=600,address=no\");return false;'> Click here </a>to View your uploaded image.";
$frm_col="black";

}
else
{
$frm_inv="Invalid file format :".$_FILES["photo"]["name"];
$frm_col="red";
}

}
else
{
$frm_inv="Invalid file format :".$_FILES["photo"]["name"];
$frm_col="red";
}


}

?>


<form action="" method="post" enctype="multipart/form-data" name="upload_frm">
<table>
<tr><td ALIGN="RIGHT">
<font face="Verdana" color="#75B04F"><strong>Image upload:</strong></FONT><br/><font face="Verdana" size="-2">(jpg, gif, png format only)</font>
</td>
<td class="td1" align="right"><input type="file" name="photo" onChange="img_uplo();"><input type="hidden" value="<?php echo $finalname; ?>" id="file"><input type="hidden" value="<?php echo $finalname; ?>" id="file1"><input type="hidden" name="subFrm" id="subFrm" value="1" />
</td>
</tr>
</table>
</form>
</body>

<script language="javascript">
function img_uplo()
{
document.upload_frm.submit();

}

</script>

</div>
<body>
</html>