实现基于DCT域的数字水印技术，可以实现水印的嵌入和提取，并具有很好的鲁棒性，mfc开发，可以在此基础实现二次开发-Based on DCT domain digital watermarking technology, we can achieve watermark embedding and extraction, and has good robustness, mfc development can be achieved on the basis of secondary devel