upload and resize multiple images with one input using php

<?php
if(isset($_POST["btn"])){
   extract($_POST);
    $error=array();
    $extension=array("jpeg","jpg","png","gif");
    foreach($_FILES["uploadedfile"]["tmp_name"] as $key=>$tmp_name)
            {
             $time=mktime(date("h"),date("i"),date("s"),date("d"));
                                            $tt=date("hisd",$time);
                                            $target_path = "photo_gallery/".$tt;
                                            $target_path = $target_path . basename( $_FILES["uploadedfile"]['name'][$key]);
                                            $target_path2 = "photo_gallery/small/".$tt;
                                            $target_path2 = $target_path2 . basename( $_FILES["uploadedfile"]['name'][$key]);
                                           /* $pn="photo_gallery/".basename( $_FILES["uploadedfile"]['name']);*/
                                            $pn="photo_gallery/".basename($_FILES["uploadedfile"]["name"][$key]);
                                            $ch=strtolower(substr($pn, strrpos($pn,".")+1));
                                                    if($ch=="jpg" or $ch=="png" or $ch=="jpeg" or $ch=="gif"){
                                                          /*  $uploadedfile = $_FILES['uploadedfile']['tmp_name'];*/
                                                           $uploadedfile = $_FILES["uploadedfile"]["tmp_name"][$key];
                                                            if (!empty($uploadedfile)){
                                                            $info = getimagesize($uploadedfile);
                                                            if($ch=="jpg" || $ch=="jpeg" )
                                                            {
                                                                    if ($info['mime'] == 'image/jpeg')
                                                            $src = imagecreatefromjpeg($uploadedfile);                       
                                                            }
                                                            else if($ch=="png")
                                                            {

                                                            if($info['mime'] == 'image/png')
                                                            $src = imagecreatefrompng($uploadedfile);

                                                            }
                                                            else
                                                            {
                                                           if($info['mime'] == 'image/gif')
                                                            $src = imagecreatefromgif($uploadedfile);
                                                            }
                                                            list($width,$height)=getimagesize($uploadedfile);
                                                            $newwidth=$width;
                                                            $newheight=$height;
                                                            $newwidth2=312;
                                                            $newheight2=($height/$width)*$newwidth2;
                                                            $tmp=imagecreatetruecolor($newwidth,$newheight);
                                                            $tmp2=imagecreatetruecolor($newwidth2,$newheight2);
                                                            if(!empty($src)){
                                                                    imagecopyresampled($tmp,$src,0,0,0,0,$newwidth,$newheight,$width,$height);
                                                                    imagecopyresampled($tmp2,$src,0,0,0,0,$newwidth2,$newheight2,$width,$height);

                                                                                                                                       $filename = "photo_gallery/".$tt.                                                                    $_FILES["uploadedfile"]["name"][$key];


                                                               
                                                            $filename2 = "photo_gallery/small/".$tt. $_FILES["uploadedfile"]["name"][$key];
                                                                    imagejpeg($tmp,$filename,100);
                                                                    imagejpeg($tmp2,$filename2,100);
                                                                    imagedestroy($src);
                                                                    imagedestroy($tmp);
                                                                    imagedestroy($tmp2);
                                                              
                                                                   
                                                            }
                                                    }
                                            }
                                    } 
            }
?>
<form enctype=multipart/form-data method='POST'>
                <input type="file" name="uploadedfile[]" multiple accept="image/*"/>
                <input type="submit" name="btn" value="upload">
           </form>