二维CAD图形可逆水印理论与方法的研究

二维CAD图形是一种矢量图形，它具有高保真与高精度等要求，因此，其安全保护应避免无法恢复的失真。可逆水印是数字内容安全保护的一种有效手段，它能无损地恢复出原始载体，故特别适合二维CAD图形的内容保护。已有可逆水印研究大多面向栅格图像和矢量地图，针对二维 CAD图形的可逆水印研究较少，且在水印容量、鲁棒性和篡改定位能力等方面还存在不足；此外，相对于其他数字内容，二维CAD图形的数据相关性低、图元类型丰富，其可逆水印的实现更为困难。基于此，本申请拟研究二维CAD图形可逆水印模型、二维CAD图形半脆弱可逆水印方法、二维CAD图形加密域可逆水印方法、二维CAD图形可逆水印性能评测方法，以及二维CAD图形可逆水印原型系统等。通过对二维CAD图形可逆水印关键技术、算法与评测方法的研究，不仅为二维CAD图形可逆水印奠定理论基础，也为网络环境下二维CAD图形的内容保护与安全认证提供一种新的有效途径。

Two-dimensional (2D) CAD graphics is a kind of vector graphics. It has high requirements in fidelity and precision, and any unrecoverable distortion should be avoided in its protection. Reversible watermarking is an effective means for the protection of digital contents. Since it can lossless recover the original host after the watermark is extracted, it is well suited for the content protection of 2D CAD graphics. The existed researches on reversible watermarking are mainly made to raster images and vector maps. However, few works have been done to 2D CAD graphics, and they still have limitations in watermark capacity, robustness and capability of tampering location. Furthermore, compared with other digital contents, the data in 2D CAD graphics have lower correlation and more abundant entity types, so the realization of its reversible watermarking is more difficult. To countermeasure these situations, this proposal will be concentrated on the research of reversible watermarking model for 2D CAD graphics, semi-fragile reversible watermarking for 2D CAD graphics, reversible watermarking for 2D CAD graphics in encryption domain, performance evaluation methods for the reversible watermarking for 2D CAD graphics, and prototype system of reversible watermarking for 2D CAD graphics. Through the research of the key technologies, algorithms and evaluation methods of 2D CAD graphics, it will not only establish a theoretical foundation for reversible watermarking for 2D CAD graphics, but also provide a novel effective means for the content protection and security authentication of 2D CAD graphics in a networked environment.