How to test if TCPDF is working correctly PS 1.7.8.2

[EngineLab]

Hi, is there a way to test if TCPDF is working correctly? Because it doesn't show the logo in the invoices, I tried to edit the header file by entering the absolute url of the jpg file (I also tried with png) it doesn't work. i wanted to upload a php file like this, (see below) to see if i generate the pdf file with the logo but i don't know the TCPDF path for the include.

best regard

  $pdf = new PDF();
  // set document information
  $pdf->SetCreator('PDF_CREATOR');
  $pdf->SetAuthor('EngineLab');
  $pdf->SetTitle($titolo);
  $pdf->SetSubject($azienda);
  $pdf->SetKeywords('Preventivo, Ordine, Fattura, Servizio');
  $pdf->AliasNbPages();
  $pdf->AddPage();     
$pdf->Image($_SERVER["DOCUMENT_ROOT"].'img/invoice-logo.jpg',10, 10, 50, 10, 'JPG', 'https://www.enginelab.it');  
  $pdf->Output('test.pdf', 'D');