// quality = 0 to 100
static byte[] toJPEGWithQuality(double quality, BufferedImage img) ctex {
  // need to drop alpha channel for this to work
  img = dropAlphaChannelFromBufferedImage(img);
  
  new ByteArrayOutputStream stream;
  var jpgWriter = first(ImageIO.getImageWritersByFormatName("jpg"));
  try {
    var params = jpgWriter.getDefaultWriteParam();
    params.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
    params.setCompressionQuality(toFloat(quality/100));
  
    jpgWriter.setOutput(new javax.imageio.stream.MemoryCacheImageOutputStream(stream));
    jpgWriter.write(null, new IIOImage(img, null, null), params);
  } finally {
    jpgWriter.dispose();
  }
  
  ret stream.toByteArray();
}

Began life as a copy of #1007587