This is my upload.php im unsure what variable im looking for

PHP Code: 
<?php


    require_once('./inc/config.php');

    if($settings['SET_DIS_UPLOAD'] && !checklogin()){
        header('Location: index.php');
        exit();
    }

// set time out timer to 10mins
    ini_set("max_execution_time", "600");
    ini_set("max_input_time", "600");

//unset session
    unset($_SESSION['upload']);
    unset($_SESSION['err']);

////////////////////////////////////////////////////////////////////////////////////
// UPLOAD CODE START

// see if user is banned
    if (db_isBanned()){
        sendError($LANGUAGE_PACK["site_upload_banned"]);
    }

// see if a image url has been posted
    if((isset($_POST['imgUrl']) && !empty($_POST['imgUrl'])) || isset($imgApiUrl)){
        $image['URL'] = input(isset($_POST['imgUrl'])?$_POST['imgUrl']:$imgApiUrl);
        require_once("lib/remoteImage.class.php");
        $remoteImage = new remoteImages($DIR_TEMP,$settings,$LANGUAGE_PACK);
        $remoteImage->validExtensions    = $imgFormats;
        $remoteImage->validType            = $acceptedFormats;
        $remoteImage->minDimensions        = $IMG_MIN_SIZE;
        $remoteImage->maxDimensions        = $IMG_MAX_SIZE;

        if($remoteImage->getImage($image['URL'])){
        //check that a file has been found and copyed to the temp dir
            if(!is_null($remoteImage->file)){
                $_FILES = $remoteImage->file;
            }
        }else{
            sendError($remoteImage->error);
        }
    }

    if(    ($_SERVER['REQUEST_METHOD'] == 'POST' ||
        isset($api)) &&
        $_FILES['file']['name'][0] !='' && 
        !isset($_SESSION['err'])){

        require_once("./lib/resize.class.php");
        require_once("./lib/phpDupeImage.php");

        $imgCount = 0;

        for($i=0; $i < count($_FILES['file']['name']);++$i){
        
        // setup image var
            $pieces        = explode("?", $_FILES['file']['name'][$i]);
            $pathInfo    = pathinfo($_FILES['file']['name'][$i]);
            $imgSize     = @getimagesize($_FILES['file']['tmp_name'][$i]);

            $image['name']    = $pieces[0];
            $image['alt']    = removeSymbols(input(!empty($_POST["alt"][$i])?$_POST["alt"][$i]:$pathInfo['filename']));
            $image['temp']    = $_FILES['file']['tmp_name'][$i];
            $image['type']    = $imgSize['mime'];
            $image['size']    = ($_FILES['file']['size'][$i] < 1?@filesize($file_tmp_name):$_FILES['file']['size'][$i]);
            $removeList[]    = $image['temp'];

        //check it's a image & set image extension
            if(!$image['ext'] = get_extension( $image['type'], false )){
                sendError(sprintf($LANGUAGE_PACK["site_upload_types_accepted"],implode(", ",$imgFormats)),'extension');
                continue;
            }

        //min size(pixels)
            if ($imgSize[0] < $IMG_MIN_SIZE || $imgSize[1] < $IMG_MIN_SIZE ){
                sendError(sprintf($LANGUAGE_PACK["site_upload_to_small"],$IMG_MIN_SIZE.'x'.$IMG_MIN_SIZE),'tosmall');
                continue;
            }

        // max size(pixels)
            if ($imgSize[0] > $IMG_MAX_SIZE || $imgSize[1] > $IMG_MAX_SIZE ){
                sendError(sprintf($LANGUAGE_PACK["site_upload_to_big"],$IMG_MAX_SIZE.'x'.$IMG_MAX_SIZE));
                continue;
            }

        //Check file size (kb)
            if($image['size'] > $settings['SET_MAXSIZE']){
                sendError(sprintf($LANGUAGE_PACK["site_upload_size_accepted"],format_size($settings['SET_MAXSIZE'])),'tobig');
                continue;
            }

        //Make Image fingerprint
            $finger = new phpDupeImage();
            $fingerprint = $finger->fingerprint($image['temp']);

        //check for Duplicate Images
            if($settings['SET_NODUPLICATE']){
            // If similar files exist, check them
                if($fp=findImage('fingerprint',$fingerprint)){
                    foreach($fp as $fpItem){
                        if ($finger->are_duplicates($image['temp'],imageAddress(1,$fpItem))){
                            $dupFound = true;
                            break;
                        }
                    }
                    if(isset($dupFound)){
                        sendError($LANGUAGE_PACK["upload_duplicate_found"],'duplicate');
                        continue;
                    }
                }
            }

        //New random name
        //Number of Possible Combinations
        //  3 digit code 46656
        //  4 digit code 1679616
        //  5 digit code 60466176
            $image['id'] = createHash(4,true);

        //random delete ID
            $image['did'] = $image['id'].createHash(6);

        //Image address
            $image['new']        = $image['id'].'.'.$image['ext'];
            $image['address']    = $DIR_IMAGE.$image['new'];

        // convert BMP to JPG and PSD to PNG
            if(in_array($image['ext'],array('psd','bmp'))){
            //Reset Image address
                $image['ext']        = ($image['ext'] == 'psd'?$PNG_SAVE_EXT:$JPG_SAVE_EXT);
                $image['new']        = $image['id'].'.'.$image['ext'];
                $image['address']    = $DIR_IMAGE.$image['new'];
            // convert psd/bmp to png
                $convert = new resize($image['temp']);
                $convert->imageConvert($image['address'],($image['ext'] == 'psd'?$PNG_QUALITY:$JPG_QUALITY));
                $convert->destroyImage();
            }
        
        //move image from remote server
            elseif(isset($image['URL']) && input($image['URL']) != ''){
                @copy($image['temp'],$image['address']);
            }
        
        //move uploaded image
            else{
                move_uploaded_file($image['temp'],$image['address']);
            }

        // move file check
            if(!file_exists($image['address'])){
                sendError($LANGUAGE_PACK["site_upload_err"].' .','filemove');
                continue;
            }

        //Resize image if needed
            if ($settings['SET_RESIZE_IMG_ON']) {

                if((isset($_POST['new_width'][$i]) && !empty($_POST['new_width'][$i])) ||
                    (isset($_POST['new_height'][$i]) && !empty($_POST['new_height'][$i]))){

                    $new_dim = new resize($image['address']);
                    $new_dim -> stretchSmallImages(TRUE);

                    if(!empty($_POST['new_width'][$i]) && !empty($_POST['new_height'][$i])){
                        $new_dim -> resizeImage($_POST['new_width'][$i], $_POST['new_height'][$i], 'exact');
                    }
                    elseif(!empty($_POST['new_width'][$i]) && empty($_POST['new_height'][$i])){
                        $new_dim -> resizeImage($_POST['new_width'][$i], $imgSize[0], 'landscape');
                    }
                    elseif(empty($_POST['new_width'][$i]) && !empty($_POST['new_height'][$i])){
                        $new_dim -> resizeImage($imgSize[1], $_POST['new_height'][$i], 'portrait');
                    }

                    $new_dim -> saveImage($image['address'],100);
                    $new_dim -> destroyImage();
                    $imgSize = @getimagesize($image['address']);// update image size for db
                }
            }


        //Thumb address
            $THUMB_ADDRESS = $DIR_THUMB.$image['new'];
            $THUMB_MID_ADDRESS = $DIR_THUMB_MID.$image['new'];

        // thumb
            $resize = new resize($image['address']);
            $resize ->setMemoryLimit ($IMG_MEMORY_LIMIT);
            $resize ->setTweakFactor ($IMG_TWEAK_FACTOR);
        // make thumb
            $resize -> resizeImage($THUMB_MID_MAX_WIDTH, $THUMB_MID_MAX_HEIGHT, $THUMB_MID_OPTION);
            $resize -> saveImage($THUMB_MID_ADDRESS, ($image['ext'] == 'png'?$PNG_QUALITY:$JPG_QUALITY));
        // make small thumb
            $resize -> resizeImage($THUMB_MAX_WIDTH, $THUMB_MAX_HEIGHT, $THUMB_OPTION);
            $resize -> saveImage($THUMB_ADDRESS, ($image['ext'] == 'png'?$PNG_QUALITY:$JPG_QUALITY));
            $resize -> destroyImage();

        //see if thumb's got made
            if(!file_exists($THUMB_ADDRESS) || !file_exists($THUMB_MID_ADDRESS)){
                @unlink($image['address']);
                @unlink($THUMB_ADDRESS);
                @unlink($THUMB_MID_ADDRESS);
                sendError($LANGUAGE_PACK["site_upload_err"].' ..','thumbmade');
                continue;
            }

        // see if we need to get a short url for the image
            if (isset($_POST['shorturl'][$i]) && $_POST['shorturl'][$i] == 1 && $settings['SET_SHORT_URL_ON']){
                $shorturl = shorturl_url('http://'.$_SERVER['HTTP_HOST'].preg_replace('/\/([^\/]+?)$/', '/', $_SERVER['PHP_SELF']).'?di='.$image['id']);
            }

        // get thumb's file size
            $image['size'] = @filesize($image['address']);
            $thumbsize = @filesize($THUMB_MID_ADDRESS);
            $sthumbsize = @filesize($THUMB_ADDRESS);

        // Make image info array to save to db
            $newImageArray = array(    'id'        => $image['id'],
                                    'name'        => $image['name'],
                                    'alt'        => $image['alt'],
                                    'added'        => time(),
                                    'ext'        => $image['ext'],
                                    'ip'        => $_SERVER['REMOTE_ADDR'],
                                    'size'        => $image['size'],
                                    'deleteid'    => $image['did'],
                                    'thumbsize' => $thumbsize,
                                    'sthumbsize'=> $sthumbsize,
                                    'private'    => (isset($_POST['private'][$i])?1:0),
                                    'report'    => 0,
                                    'shorturl'    => (!isset($shorturl)?null:$shorturl),
                                    'fingerprint'  =>$fingerprint,
                                    );

        //save new image to database
            if(addNewImage($newImageArray)){

            // save image to upload array to be sent to thumb page
                $_SESSION['upload'][] = array('id' => $image['id'],'did' => $image['did']);

            // count images uploaded
                $imgCount++;
                if($imgCount >= $settings['SET_MAX_UPLOAD'] && !checklogin()){
                    break; // break upload loop as you have updated max number of images in one go...
                }

            }else{
                sendError($LANGUAGE_PACK["site_index_delete_image_err_db"],'savedb');
                continue;
            }
        }// end image upload loop
    }
// error uploading image
    elseif(!isset($_SESSION['err'])){
        sendError($LANGUAGE_PACK["site_upload_err"].' ...','uk');
    }

// remove temp images
    if(isset($removeList)){
        foreach ($removeList as $tempImg){
            // remove old file
                if(file_exists($tempImg)){
                    unlink($tempImg);
                }
        }
    }

// UPLOAD CODE END
////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////
// MAKE PAGE

// error send back to home page and show the error
    if(!isset($_SESSION['upload'])){
        header('Location: '. $settings['SET_SITEURL'].'/index.php');
        exit();
    }

// open thumb page and show upload images
    header('Location: '. $settings['SET_SITEURL'].'/thumbnail.php');
    die();


// MAKE PAGE END
////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////
// functions

// send error back to index page
    function sendError($msg,$id=''){
        $_SESSION['err'][$id] = $msg;
    }

// get file ext from mine
    function get_extension($imagetype, $includeDot = false){
        global $acceptedFormats;
        if(empty($imagetype)) return false;
        $dot = $includeDot ? '.' : '';
        if(isset($acceptedFormats[$imagetype])){
            return $dot.$acceptedFormats[$imagetype];
        }
        return false;
    }


// very simple hash function to generate a random string
    function createHash($length=5,$check=null){
        $valid    = 0;
        $hash    = '';
        while(!$valid){
            for($i=0;$i<$length;++$i){
            // if you want to add letters you will have to change the id to varchar instead of int
                $possibleValues = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
            // pick a random character from the possible ones
                $hash .= substr($possibleValues, mt_rand(0, strlen($possibleValues)-1), 1);
            }
        // checks if the hash allready exists in the db
            if(is_null($check) || !getImage($hash)){
                $valid = 1;
            }
        }
        return $hash;
    }