Crop and letterbox PHP GD image

ssllogo.php

<?php

$url = $_REQUEST['image'];
$max_width = 500;
$max_height = 500;

$ch = curl_init();

curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch,CURLOPT_CONNECTTIMEOUT,5);

$data = curl_exec($ch);

$http_returned_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
@$im = imagecreatefromstring($data);

curl_close($ch);


if(!$im || $http_returned_code == 404 || $http_returned_code == 307 || $http_returned_code == 403 || $http_returned_code == 500 || $http_returned_code == 0 || $http_returned_code == 400) {

  $url = $_SERVER["SERVER_NAME"] . '/images/default_logos/default_icon_whitebg.jpg';

	$ch = curl_init();
	curl_setopt($ch,CURLOPT_URL,$url);
	curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
	curl_setopt($ch,CURLOPT_CONNECTTIMEOUT,5);

	$data = curl_exec($ch);

	$im = imagecreatefromstring($data);

	curl_close($ch);
}


$width = imagesx($im);
$height = imagesy($im);

if ($height > $width) {
	$ratio = $max_height / $height;
	$x = $width * $ratio;
	$y = $max_height;
	$pos_x = round(($max_height - $x) / 2);
	$pos_y = 0;
} else {
	$ratio = $max_width / $width;
	$x = $max_width;
	$y = $height * $ratio;
	$pos_x = 0;
	$pos_y = round(($max_width - $y) / 2);
}

header("Content-Type: image/png");

$im_resize = imagecreate($max_width, $max_height);

imagecolorallocate($im, 255, 255, 255);
imagecopyresized($im_resize, $im, $pos_x, $pos_y, 0, 0, $x, $y, $width, $height);
imagedestroy($im);
imagepng($im_resize);
imagedestroy($im_resize);