static void saveBMP(BufferedImage img, File file) ctex {
  // drop alpha component
  BufferedImage newBufferedImage = new BufferedImage(img.getWidth(), 
  img.getHeight(), BufferedImage.TYPE_INT_RGB);
  newBufferedImage.createGraphics().drawImage(img, 0, 0, Color.WHITE, null);
  
  assertTrue("BMP writing failed", ImageIO.write(newBufferedImage, "bmp", mkdirsFor(file)));
}

static void saveBMP(File file, BufferedImage img) ctex {
  saveBMP(img, file);
}