title: PHP font_size Captcha issue
body: <p>I tried to change the <code>$font_size</code> but it seems it is not working. It stays the same no matter what. Even if I altered the <code>$font_size</code> up to 130. It stays the same: </p>
  
  <pre><code>&lt;?php
      header('Content-type: image/png');
  
      $rand_num = rand(1000, 9999);
  
      $font_size = 130;
  
      $image_width = 110;
      $image_height = 20;
  
      $image = imagecreate($image_width, $image_height);
      imagecolorallocate($image, 255, 255, 255);
      $black_color = imagecolorallocate($image, 0, 0, 0);
  
      imagestring($image, $font_size, 0, 0, $rand_num, $black_color);
  
      for($x=0; $x &lt;= 30; $x++){
          $x1 = rand(1, 100); 
          $y1 = rand(1, 100);
          $x2 = rand(1, 100);
          $y2 = rand(1, 100);
  
          imageline($image, $x1, $y1, $x2, $y2, $black_color);
      }
  
      imagepng($image);
  ?&gt;
  </code></pre>