function convertImageToPDF(filename) {
  var image;

  // Is it a local file or web URL?
  if (filename.match(/^https?:\/\//i)) {
    image = UrlFetchApp.fetch(filename);
  } else {
    image = DriveApp.getFilesByName(filename).next();
  }

  // grab its bytes and base64-encode them.
  var base64 = Utilities.base64Encode(image.getBlob().getBytes());
  var html = '<img src="data:image/png;base64,' + base64 + '" />';

  // create a blob, convert to PDF
  var blob = Utilities.newBlob(html, MimeType.HTML).setName(filename + '.pdf');

  MailApp.sendEmail('ctrlq@labnol.org', 'Image to PDF', '', {
    attachments: blob.getAs(MimeType.PDF),
  });
}