title: How to save an image created from imagecreatefromstring() function?
body: <p>Here is my code:</p>
  
  <pre><code>$data = 'iVBORw0KGgoAAAANSUhEUgAAABwAAAASCAMAAAB/2U7WAAAABl'
         . 'BMVEUAAAD///+l2Z/dAAAASUlEQVR4XqWQUQoAIAxC2/0vXZDr'
         . 'EX4IJTRkb7lobNUStXsB0jIXIAMSsQnWlsV+wULF4Avk9fLq2r'
         . '8a5HSE35Q3eO2XP1A1wQkZSgETvDtKdQAAAABJRU5ErkJggg==';
  $data = base64_decode($data);
  
  $im = imagecreatefromstring($data);
  if ($im !== false) {
      header('Content-Type: image/png');
      imagepng($im);
      imagedestroy($im);
  
  }
  else {
      echo 'An error occurred.';
  }
  </code></pre>
  
  <p>I'd like to save the image generated this way to a directory. How do I do this?</p>