Create Thumbnail of image in php

<?php


if($_FILES['user_image']['type'] == "image/jpeg" && $_FILES['user_image']['size'] < 3000000)
{

    $target_folder = 'images/'; // This is the folder to which the images will be saved
   
    $upload_image = $target_folder.basename($_FILES['user_image']['name']); // The new file location


    if(move_uploaded_file($_FILES['user_image']['tmp_name'], $upload_image))
    {
          $newname =$_FILES['user_image']['name']; // Get the supplied image name and sanitize it
       
           $thumbnail = $target_folder."_thumbnail".$newname; // Set the thumbnail name
        $actual = $target_folder.$newname; // Set the actual image name
       
        // Get new sizes
        list($width, $height) = getimagesize($upload_image);
        $newwidth = 150; // This can be a set value or a percentage of original size ($width)
        $newheight = 150; // This can be a set value or a percentage of original size ($height)
       
        // Load the images
        $thumb = imagecreatetruecolor($newwidth, $newheight);
        $source = imagecreatefromjpeg($upload_image);

        // Resize the $thumb image.
        imagecopyresized($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
       
        // Save the new file to the location specified by $thumbnail
        imagejpeg($thumb, $thumbnail, 100);
       
        // Rename the original
        //note, this only needs to be done if a new filename is supplied in the form (As it is in this example).
        // note 2, if you don't mind starting the mysql connection earlier than the file move in order to sanitize $_POST['image_name'], $upload_image can use
        // $newname from the beginning instead of $_FILES['user_image']['name'] in line 12.
       
       
        // Now we will try and insert the details into the database with the new actual and thumbnail files, and with the new caption...
        // We carry out the mysql query as part of an IF statement to evaluate if it worked properly.
       
       
            // ...it did work properly.  Tell the user and do anything else you particularly feel like doing.
            ?>
            <p>Image Successfully uploaded!<br />Actual image: <?=$actual;?><br />Thumbnail image: <?=$thumbnail;?><br />Caption: <?=$caption;?></p>
            <?php
       
       
    }
    else
    {
        // There was a problem with the file and it wasn't moved to the server.
        ?>
        <p>Error processing file.  It may be too large.</p>
        <?php
    }
}
else
{
        // The file was the wrong format or size
        ?>
        <p>Error processing file.  It is the wrong format (.jpeg only) or too big.</p>
        <?php
}
?>

<form enctype="multipart/form-data" action="" method="POST">
    What would you like to call the image?: <input type="text" name="image_name" id="image_name" />
    <br />
    What caption should the image have?: <input type="text" name="image_caption" id="image_caption" />
    <br />
    <input type="hidden" name="MAX_FILE_SIZE" value="3000000" />
    Pick an Image from your computer: <input name="user_image" type="file" />
    <br />
    <input type="submit" value="Upload" />
</form>