更改图像大小 - PHP

我最近创建了一个上传功能，但我不知道如何将宽度和高度更改为 75px...我尝试了通过 Google 找到的一个代码，但我刚刚收到此错误：

( ! ) Fatal error: Class 'Imagick' not found in C:\wamp\www\Legendary\new\usersettings.php on line 725
Call Stack
#   Time    Memory  Function    Location
1   0.0042  880616  {main}( )   ..\usersettings.php:0

这是我当前的代码（包括不起作用的代码）：

echo '
                    <table border="0" width="100%">
                    <tr><td style="font-size: 16px;">Change Image</td></tr>

                    <form action="" method="post" enctype="multipart/form-data">
                        <tr><td>Upload Image:</td><td style="text-align: right;"><input type="file" name="upimage" id="upimage" /></td></tr>
                        <tr><td></td><td style="text-align: right; font-size: 10px;"></td></tr>
                        <tr><td></td><td style="text-align: right;"><input type="submit" name="submitnewimage" value="Upload" class="button" /></td></tr>
                    </form>
                    ';

                    echo '
                    </table>
                    ';

                    if(isset($_POST['submitnewimage'])){
                        $name = $_FILES['upimage']['name'];
                        $temp = $_FILES['upimage']['tmp_name'];
                        $type = $_FILES['upimage']['type'];
                        $size = $_FILES['upimage']['size'];
                        if($name!=""){
                            include 'config.php';
                            $sql5 = mysql_query("SELECT * FROM images ORDER BY id DESC LIMIT 1");
                            while($row=mysql_fetch_array($sql5)) {
                                if(!isset($show2)){
                                    $id = $row['id'];
                                    $id = $id + 1;

                                    $show2 = "YES";
                                }
                            }

                            if(($type=="image/jpeg") || ($type=="image/jpg") || ($type=="image/gif") || ($type=="image/pjpeg") || ($type=="image/png")){
                                if($size<=100000){
                                    $pos = strrpos($name, '.');
                                    if($pos === false)
                                        $ext = "";
                                    $ext = substr($name, $pos);
                                    $newFilename = $id.$ext;

                                    move_uploaded_file($temp, "images/teamicons/".$newFilename);
                                    $im = new Imagick('images/teamicons/'.$newFilename); 
                                    $im->thumbnailImage(75,75); 
                                    $im->writeImage('images/teamicons/'.$newFilename);

                                    mysql_query("INSERT INTO `images`(`id`, `name`, `size`, `type`) VALUES (NULL,'$newFilename',$size,'$type')");
                                    $myusername = $_SESSION['myusername'];
                                    mysql_query("UPDATE `members` SET `img`= '$newFilename' WHERE `username`='$myusername'");

                                    header("Location:" . $_SESSION['prev_page']);
                                }else{echo "<tr><td colspan='2'><span style='color:#F00;'>The file, &quot;".$name."&quot;, is too large! Maximum allowed file size is 100kB.</span></td></tr>";}
                            }else{echo "<tr><td colspan='2'><span style='color:#F00;'>&quot;".$type."&quot; is not a valid file type!</span></td></tr>";}
                        }else{echo "<tr><td colspan='2'><span style='color:#F00;'>No file has been specified!</span></td></tr>";}
                    }

有没有办法改变图像的宽度和高度？

我已经成功使用了GD最近要做到这一点，特别是使用imagecopyresampled功能。

为了扩展一点......一旦我上传了图像（我不会详细讨论，因为这是一个完全不同的问题），我做了一些相当简单的事情，如下所示：

$original_info = getimagesize($filename);
$original_w = $original_info[0];
$original_h = $original_info[1];
$original_img = imagecreatefromjpg($filename);
$thumb_w = 100;
$thumb_h = 100;
$thumb_img = imagecreatetruecolor($thumb_w, $thumb_h);
imagecopyresampled($thumb_img, $original_img,
                   0, 0,
                   0, 0,
                   $thumb_w, $thumb_h,
                   $original_w, $original_h);
imagejpeg($thumb_img, $thumb_filename);
imagedestroy($thumb_img);
imagedestroy($original_img);

请注意，我尚未测试此代码。在这里只是为了让您对我的方法有一个基本的了解。