提出一种基于DCT 变换的半脆弱数字水印算法研究。该算法将原始图像进行分割，通过DCT 变换生成水 印，基于密钥生成矩阵并嵌入到图像块中。利用被篡改的图像半色调图和提取水印的差异进行篡改定位。实验仿真结果表 明，该算法篡改定位精度较高。

This paper puts forward an algorithm of semi fragile digital watermarking based on DCT conversion. The origial image is splited and generates watermark by DCT conversion. And the image blocks are embedded with matrix generated by the keys. It utilizes the differences between the distorted halftone image and the extracted watermark to locate the tempering position. The experiments show that this algorithm gets high accuracy of the temper location.