static File jpegify(File imageFile, bool makeBackup default true) {
  if (isJPEGFile(imageFile)) ret imageFile;
  loading "JPEGify" {
    BufferedImage img = loadImage2(imageFile);
    File destFile = replaceExtension(imageFile, ".jpg");
    File atticFile = makeBackup ?
      newFile(javaxDataDir("JPEGified original pictures"), imageFile.getName()) : null;
    if (makeBackup)
      atticFile = makeFileNameUnique(atticFile);
    saveJPGVerbose(destFile, img);
    if (makeBackup)
      moveFileVerbose(imageFile, atticFile);
    else
      deleteFile(imageFile);
    print("Conversion done.");
    ret destFile;
  }
}