def _pdf_to_png(self, pdf_file_path, rendered_file_path, page, dpi=96):

        # PDF-to-image utility
        # look for Poppler w/ Cairo, then muPDF
        # * Poppler w/ Cairo renders correctly
        # * Poppler w/o Cairo does not always correctly render vectors in PDF to image
        # * muPDF renders correctly, but slightly shifts colors
        for util in [
            'pdftocairo',
            # 'mudraw',
        ]:
            PDFUTIL = getExecutablePath(util)
            if PDFUTIL:
                break

        # noinspection PyUnboundLocalVariable
        if not PDFUTIL:
            assert False, ('PDF-to-image utility not found on PATH: '
                           'install Poppler (with Cairo)')

        if PDFUTIL.strip().endswith('pdftocairo'):
            filebase = os.path.join(
                os.path.dirname(rendered_file_path),
                os.path.splitext(os.path.basename(rendered_file_path))[0]
            )
            call = [
                PDFUTIL, '-png', '-singlefile', '-r', str(dpi),
                '-x', '0', '-y', '0', '-f', str(page), '-l', str(page),
                pdf_file_path, filebase
            ]
        elif PDFUTIL.strip().endswith('mudraw'):
            call = [
                PDFUTIL, '-c', 'rgba',
                '-r', str(dpi), '-f', str(page), '-l', str(page),
                # '-b', '8',
                '-o', rendered_file_path, pdf_file_path
            ]
        else:
            return False, ''

        print("exportToPdf call: {0}".format(' '.join(call)))
        try:
            subprocess.check_call(call)
        except subprocess.CalledProcessError as e:
            assert False, ("exportToPdf failed!\n"
                           "cmd: {0}\n"
                           "returncode: {1}\n"
                           "message: {2}".format(e.cmd, e.returncode, e.message))