upload.php

<?php
// disable error if you want
//error_reporting(0);

include_once('includes/config.php');
include_once('includes/functions.php');

if ($_GET['act'] == 'thumb') {
    $arr = array(
        'uploaddir' => $imgthumb,
        'tempdir' => $imgtemp,
        'height' => $_POST['height'],
        'width' => $_POST['width'],
        'x' => $_POST['x'],
        'y' => $_POST['y'],
        'img_src' => $_POST['img_src'],
        'thumb' => true,
        'fileError' => $fileError,
        'sizeError' => $sizeError,
        'maxfilesize' => $maxuploadfilesize,
        'canvasbg' => $canvasbg,
        'bigWidthPrev' => $bigWidthPrev,
        'bigHeightPrev' => $bigHeightPrev,
    );
    resizeThumb($arr);
    exit;
} elseif ($_GET['act'] == 'upload') {

    $big_arr = array(
        'uploaddir' => $imgbig,
        'tempdir' => $imgtemp,
        'height' => $_POST['height'],
        'width' => $_POST['width'],
        'x' => 0,
        'y' => 0,
        'thumb' => false,
        'fileError' => $fileError,
        'sizeError' => $sizeError,
        'maxfilesize' => $maxuploadfilesize,
        'canvasbg' => $canvasbg,
        'bigWidthPrev' => $bigWidthPrev,
        'bigHeightPrev' => $bigHeightPrev,
    );

    resizeImg($big_arr);
} else {
    //nothing to do here
}