如何在没有功能的情况下压缩图像

我总是在上传图像之前用 http://compressjpeg.com/压缩图像，这不是很实用。我想用 php 制作一个像 http://compressjpeg.com/这样的压缩器。

我有这个代码

<?php
require '../../db/sessions.php';
require '../../db/ds.php';
$path = "../../image/color/aqua/";

    $valid_formats = array("jpg", "png", "gif", "bmp");
    if(isset($_POST) and $_SERVER['REQUEST_METHOD'] == "POST" )
        {
            $name = $_FILES['aqua-example']['name'];
            $size = $_FILES['aqua-example']['size'];
            $code = $_POST['aqua-code'];
            if(strlen($name))
                {
                    list($txt, $ext) = explode(".", $name);
                    if(in_array($ext,$valid_formats))
                    {
                    if($size<(1024*1024))
                        {
                            $ext = "jpg";
                            $actual_image_name = $code.".".$ext;
                            $tmp = $_FILES['aqua-example']['tmp_name'];
                            if(move_uploaded_file($tmp, $path.$actual_image_name))
                                {
                                    $query = "UPDATE waiting_item SET aqua='$actual_image_name' WHERE id='$code'";
                                    $res = $mysqli->query($query);  
                                    echo "<img src='/image/color/aqua/".$actual_image_name."' width='400' height='400' class='ua6m u766 ".$actual_image_name."'>";
                                }
                            else
                                echo "failed";
                        }
                        else
                        echo "Image file size max 1 MB";                    
                        }
                        else
                        echo "Invalid file format..";   
                }
            else
                echo "Please select image..!";
            exit;
        }
?>

有没有办法在不使用函数的情况下进行压缩？ 也许是代码太多了。以及如何创建两个不同大小的图像？例如图像A=900px x 600px和B=120px x 500px？谢谢

编辑

<?php
require '../../db/sessions.php';
require '../../db/ds.php';
$path = "../../image/color/aqua/";

    $valid_formats = array("jpg", "png", "gif", "bmp");
    if(isset($_POST) and $_SERVER['REQUEST_METHOD'] == "POST" )
        {
            $name = $_FILES['aqua-example']['name'];
            $size = $_FILES['aqua-example']['size'];
            $code = $_POST['aqua-code'];
            if(strlen($name))
                {
                    list($txt, $ext) = explode(".", $name);
                    if(in_array($ext,$valid_formats))
                    {
                    if($size<(1024*1024))
                        {
                            $ext = "jpg";
                            $actual_image_name = $code.".".$ext;
                            $tmp = $_FILES['aqua-example']['tmp_name'];
                            if(move_uploaded_file($tmp, $path.$actual_image_name))
                                {
// --------------------------------- THIS ----------------------------- //

    function Img_Resize($paths) {
       $x = getimagesize($paths);            
       $width  = $x['0'];
       $height = $x['1'];
       $rs_width  = $width / 2;
       $rs_height = $height / 2;
       switch ($x['mime']) {
          case "image/gif":
             $img = imagecreatefromgif($paths);
             break;
          case "image/jpeg":
             $img = imagecreatefromjpeg($paths);
             break;
          case "image/png":
             $img = imagecreatefrompng($paths);
             break;
       }
       $img_base = imagecreatetruecolor($rs_width, $rs_height);
       imagecopyresized($img_base, $img, 0, 0, 0, 0, $rs_width, $rs_height, $width, $height);
       $path_info = pathinfo($paths);    
       switch ($path_info['extension']) {
          case "gif":
             imagegif($img_base, $paths);  
             break;
          case "jpeg":
             imagejpeg($img_base, $paths);  
             break;
          case "png":
             imagepng($img_base, $paths);  
             break;
       }
    }
$img = Img_Resize($path,$actual_image_name);
// ------------------ end ----------------------------- //
                                    $query = "UPDATE waiting_item SET aqua='$actual_image_name' WHERE id='$code'";
                                    $res = $mysqli->query($query);  
                                    echo "<img src='/image/color/aqua/".$actual_image_name."' width='400' height='400' class='ua6m u766 ".$actual_image_name."'>";
                                }
                            else
                                echo "failed";
                        }
                        else
                        echo "Image file size max 1 MB";                    
                        }
                        else
                        echo "Invalid file format..";   
                }
            else
                echo "Please select image..!";
            exit;
        }
?>