Can't get file contents with GET but can with POST

I'm building an application in Laravel that requires users to upload documents. To maintain a high level of security around these documents, they must be stored in the "private" storage. I'm able to upload and store them successfully and I can access the file contents if I use a Route with a POST however if I try to use a GET method in an img src tag to display an image inline the image doesn't render.

What I have noticed is if I copy and paste the image location (by inspecting the rendered view) into another browser tab, the token is completely different, the browser tab is effectively not logged in, so the image is unavailable and I get a 404 error. This is fine in terms of protecting the documents and I'm very happy about that, but I would really like the image to be able to display inline as well.

No suggestions about using public storage etc, this will not work for my application.

Code is as follows: In the blade

<img src="{{ route('showJpg',$document->filename) }}" class="img-responsive" width="100%">

Sample output from rendered view

<img src="http://nzm.local/admin/showImage/Wilson-Family/KzzaeTBaeORqgr8SFbLE7B4ODF5P2waGlvC7vS7F.jpeg" class="img-responsive" width="100%">

POST Method (takes Request as parameter)

  public function getFile(Request $request)
  {
      $filename = $request->filename;
      $file = Storage::get($filename);

      if ($file) {

        $ext = pathinfo($filename, PATHINFO_EXTENSION);
        $header[] = ($ext=="pdf" ? "'Content-Type', 'application/pdf'" : "'Content-Type', 'image/jpeg'");

        return response()->file(storage_path('/app/'.$filename), $header);

      } else {
        dd("No file");
      }
  }

GET Method (takes filename as parameter)

  public function viewjpg($filename)
  {
    //
    $file = Storage::get($filename);

    if ($file) {

      $ext = pathinfo($filename, PATHINFO_EXTENSION);
      $header[] = ($ext=="pdf" ? "'Content-Type', 'application/pdf'" : "'Content-Type', 'image/jpeg'");

      return response()->file(storage_path('/app/'.$filename), $header);

    } else {
      dd("No file");
    }
  }

Neither of these methods hit the dd("No file") as the image exists and is clearly readable by the application. The problem is with the GET method and the token, as far as I tell.

Any assistance greatly appreciated, have been chasing my own tail for a while now and not making any headway at all.