说明：  这个程序是基于DCT域的数字水印嵌入程序的提取程序，不需要原始图像，就可以从加水印的图像中提取水印图像
(This procedure is based on the DCT domain of the digital watermark embedding process of the extraction procedure does not require the original image, you can add a watermark image from the extracted watermark image)