为了解决图片类信息加密易破解的问题，更好地对相关产品的版权加以保护，采用一种基于分块离散余弦变换 (DCT)的数字盲水印算法。图像经分块后先进行 DCT变换，从空域变换到频域，然后进行水印的嵌入和提取，最后与基于小波变换域的数字水印算法的实验进行对比。研究表明，该算法在峰值信噪比为 52.588 3 dB时，可以为图像提供良好的水印透明性，且对噪声、剪切等攻击有明显的抵抗效果，同时具有良好的鲁棒性。

In order to solve the problem that the encrypted image can be cracked easily and protect the copyright of related products, this paper adopts a digital blind watermarking algorithm based on block DCT transform. After the image is divided into blocks, the DCT transform is performed, and the spatial domain is transformed into the frequency domain. Then, we can embed and extract the watermark into the image. Finally, in the experiment about the digital watermarking algorithm based on wavelet transform domain, we found that the proposed algorithm can provide good watermark transparency for images with peak signal-to-noise ratio of 52.588 3 dB. And it has good performance to avoid noise and shear. This method has good robustness.