title: Trying to use khanamiryan's php-qrcode-detector-decoder on apache2 / php7
body: <p>I am trying to use khanamiryan's php library for reading QR codes from image files;
  <a href="https://github.com/khanamiryan/php-qrcode-detector-decoder" rel="nofollow noreferrer">https://github.com/khanamiryan/php-qrcode-detector-decoder</a></p>
  
  <p>Currently I am unable to get it working on Debian Stretch (specifically Raspbian Stretch on a Raspberry Pi 3B). I can only get HTTP 500 errors.</p>
  
  <p>Clean install of Raspbian Stretch, then the following in a terminal;</p>
  
  <pre><code>sudo apt-get install apache2 php libapache2-mod-php php7.0-gd composer
  cd /var/www/html
  composer require khanamiryan/qrcode-detector-decoder
  </code></pre>
  
  <p>Here's the php I am trying to run;</p>
  
  <pre class="lang-php prettyprint-override"><code>&lt;?php
  require __DIR__ . "/vendor/autoload.php";
  $qrcode = new QrReader('test.png');
  $text = $qrcode-&gt;text();
  print($text);
  ?&gt;
  </code></pre>
  
  <p>Expected result is the text from the QR code in the image test.png is written to the response but I always get HTTP 500 error.</p>
  
  <p>Any suggestions? Do I need to install some underlying C++ or Java library?</p>