imagettftext无法正常工作 - 根本没有打印图像

Question

I'm trying to write text onto an image using PHP / imagettftext. Unfortunately the below code isn't working. Things to note:

• The font IS in the directory and is detected by PHP when I ran a function to check the file exists. I've missed off the ".ttf" extension as apparently you don't need this if the font is in the same directory as the script.

• If I comment out the imagettftext, the background image prints no problem.

• I'm able to write text using imagestring successfully.

This is what appears when imagettftext is used: Any ideas?

 header('Content-type: image/jpeg');

  // Create Image From Existing File
  $png_image = imagecreatefrompng('background.png');

  // Allocate A Color For The Text
  $white = imagecolorallocate($png_image, 255, 255, 255);

  // Set Path to Font File
  $font_path = 'DIN';

  // Set Text to Be Printed On Image
  $text = "This is a sunset!";

  // Print Text On Image
  imagettftext($png_image, 25, 0, 75, 300, $white, $font_path, $text);
  // Send Image to Browser
  imagejpeg($png_image);

  // Clear Memory
  imagedestroy($png_image);