code: public static void gray(Image srcImage, ImageOutputStream destImageStream) throws IORuntimeException {
  		writeJpg(gray(srcImage), destImageStream);
  	}
docs: 彩色转为黑白<br>
  此方法并不关闭流
  
  @param srcImage 源图像流
  @param destImageStream 目标图像流
  @since 3.0.9
  @throws IORuntimeException IO异常