Проблемы с сохранением прозрачности при загрузке скрипта

Так что я не уверен, что я делаю неправильно, я думал, что у меня это отлично работает, пока я не загрузил PNG с прозрачным фоном, а потом сохранил с черным фоном. Кто-нибудь может указать, что я делаю не так? Вот мой класс изображений и код загрузки. Я думал, что раздел imagecreatefrompng — это то, что сохранит прозрачность, но, возможно, я ошибаюсь или делаю это неправильно?

Класс изображения

    <?php
ini_set("memory_limit","50M");

function normal_resize_image($source, $destination, $image_type, $max_size, $image_width, $image_height, $quality){

if($image_width <= 0 || $image_height <= 0){return false;} //return false if nothing to resize

//do not resize if image is smaller than max size
if($image_width <= $max_size && $image_height <= $max_size){
if(save_image($source, $destination, $image_type, $quality)){
return true;
}
}

//Construct a proportional size of new image
$image_scale    = min($max_size/$image_width, $max_size/$image_height);
$new_width      = ceil($image_scale * $image_width);
$new_height     = ceil($image_scale * $image_height);

$new_canvas     = imagecreatetruecolor( $new_width, $new_height ); //Create a new true color image
imagealphablending($new_canvas,true);

//Copy and resize part of an image with resampling
if(imagecopyresampled($new_canvas, $source, 0, 0, 0, 0, $new_width, $new_height, $image_width, $image_height)){
save_image($new_canvas, $destination, $image_type, $quality); //save resized image
}

return true;
}

function thumb_resize_image($source, $destination, $image_type, $max_size, $image_width, $image_height, $quality){

if($image_width <= 0 || $image_height <= 0){return false;} //return false if nothing to resize

//do not resize if image is smaller than max size
if($image_width <= $max_size && $image_height <= $max_size){
if(save_image($source, $destination, $image_type, $quality)){
return true;
}
}

//Construct a proportional size of new image
$image_scale    = min($max_size/$image_width, $max_size/$image_height);
$new_width      = ceil($image_scale * $image_width);
$new_height     = ceil($image_scale * $image_height);

$new_canvas     = imagecreatetruecolor( $new_width, $new_height ); //Create a new true color image
imagealphablending($new_canvas,true);

//Copy and resize part of an image with resampling
if(imagecopyresampled($new_canvas, $source, 0, 0, 0, 0, $new_width, $new_height, $image_width, $image_height)){
save_image($new_canvas, $destination, $image_type, $quality); //save resized image
}

return true;
}

##### This function corps image to create exact square, no matter what its original size! ######
function crop_image_square($source, $destination, $image_type, $square_size, $image_width, $image_height, $quality){
if($image_width <= 0 || $image_height <= 0){return false;} //return false if nothing to resize

if( $image_width > $image_height )
{
$y_offset = 0;
$x_offset = ($image_width - $image_height) / 2;
$s_size     = $image_width - ($x_offset * 2);
}else{
$x_offset = 0;
$y_offset = ($image_height - $image_width) / 2;
$s_size = $image_height - ($y_offset * 2);
}
$new_canvas = imagecreatetruecolor( $square_size, $square_size); //Create a new true color image
imagealphablending($new_canvas,true);

//Copy and resize part of an image with resampling
if(imagecopyresampled($new_canvas, $source, 0, 0, $x_offset, $y_offset, $square_size, $square_size, $s_size, $s_size)){
save_image($new_canvas, $destination, $image_type, $quality);
}

return true;
}

##### Saves image resource to file #####
function save_image($source, $destination, $image_type, $quality){
switch(strtolower($image_type)){//determine mime type
case 'image/png':
imagepng($source, $destination); return true; //save png file
break;
case 'image/gif':
imagegif($source, $destination); return true; //save gif file
break;
case 'image/jpeg': case 'image/pjpeg':
imagejpeg($source, $destination, $quality); return true; //save jpeg file
break;
default: return false;
}
}
?>

Вот код для загрузки.

if(isset($_POST['addImages'])) {
$valid_formats = array("jpg", "jpeg", "png", "gif", "bmp", "JPG", "JPEG", "PNG", "GIF", "BMP");
$max_file_size = 50971520; //50mb
$path = "images/media/"; // Upload directory
$count = 0;

$thumb_square_size = 300; //Thumbnails will be cropped
$max_image_size = 1200; //Maximum image size (height and width)
$thumb_prefix = "_thumb"; //Normal thumb Prefix
$destination_folder = 'images/media/'; //upload directory ends with / (slash)
$jpeg_quality = 90; //jpeg quality

// Loop $_FILES to execute all files
foreach ($_FILES['files']['name'] as $foto => $name) {
if ($_FILES['files']['error'][$foto] == 4) {
continue; // Skip file if any error found
}
if ($_FILES['files']['error'][$foto] == 0) {
if ($_FILES['files']['size'][$foto] > $max_file_size) {
$message[] = "$name is too large!.";
continue; // Skip large files
}
elseif( ! in_array(pathinfo($name, PATHINFO_EXTENSION), $valid_formats) ){
$message[] = "$name is not a valid format";
continue; // Skip invalid file formats
}
else { // No error found!
$image_name = $name; //file name
$image_size = $_FILES['files']['size'][$foto]; //file size
$image_temp = $_FILES['files']['tmp_name'][$foto]; //file temp
$image_size_info = getimagesize($image_temp); //get image size

if($image_size_info){
$image_width = $image_size_info[0]; //image width
$image_height = $image_size_info[1]; //image height
$image_type = $image_size_info['mime']; //image type
} else {
die("Make sure image file is valid!");
}

//switch statement below checks allowed image type as well as creates new image from given file.
switch($image_type){
case 'image/png':
$image_res = imagecreatefrompng($image_temp);
imageAlphaBlending($image_res, true);
imageSaveAlpha($image_res, true);
break;
case 'image/gif':
$image_res = imagecreatefromgif($image_temp); break;
case 'image/jpeg': case 'image/pjpeg':
$image_res = imagecreatefromjpeg($image_temp); break;
default:
$image_res = false;
}

if($image_res){
//Get file extension and name to construct new file name
$image_info = pathinfo($image_name);
$image_extension = strtolower($image_info["extension"]); //image extension
$image_name_only = strtolower($image_info["filename"]);//file name only, no extension
$dateRec = date('d-M-Y-h-i-s');

//create a random name for new image (Eg: fileName_293749.jpg) ;
$new_file_name = $dateRec. '_' .  rand(0, 9999999999);
//folder path to save resized images and thumbnails
$thumb_save_folder  = $destination_folder . $new_file_name . $thumb_prefix . '.' . $image_extension ;
$image_save_folder  = $destination_folder . $new_file_name. '.' . $image_extension;

//call normal_resize_image() function to proportionally resize image
if(normal_resize_image($image_res, $image_save_folder, $image_type, $max_image_size, $image_width, $image_height, $jpeg_quality)) {
//call crop_image_square() function to create square thumbnails
if(!thumb_resize_image($image_res, $thumb_save_folder, $image_type, $thumb_square_size, $image_width, $image_height, $jpeg_quality)) {
die('Error Creating thumbnail');
}

}
}

$post_img = $new_file_name.'.'.$image_extension;
$post_img_thumb = $new_file_name.$thumb_prefix.'.'.$image_extension;
$stmt = $mysqli->prepare('INSERT INTO media_images(image, image_thumb, members_id) VALUES (?,?,?)');
$stmt->bind_param('ssi', $post_img, $post_img_thumb, $members_id);
$stmt->execute();
$stmt->close();

$count++;
}
}
}
$MEMUS = memory_get_usage();
ob_start();
header("Location: media.php");
}