The Research On 2D Engineering Graphics Watermarking Technology Of Copyright Protection Based On Transform Domain

The existing watermarking methods for two-dimensional engineering graphics are of low embedding capacity, inferior robustness, and also non-blind which are greatly restricts their practical application, so more efforts should be dedicated to this type of watermarking in order to develop new algorithms which are able to avoid those drawbacks in the previous watermarking approaches and thus to achieve the purpose of copyright protection.This paper makes a deep investigation into the two-dimensional engineering graphic-based watermarking techniques. The background, feature, classification and current research status of the two-dimensional engineering graphic watermarking are first presented, followed by analyzing the shortcomings in the existing watermarking. And then, the relevant theoretical knowledge, including Chaos Theory, Fourier Transform and Wavelet Transform, and their respective features are introduced. Finally, two watermarking schemes are proposed, based on the current research status of the two-dimensional engineering graphic watermarking.A complex number system-based two-dimensional engineering graphic watermarking with variable capacity is first proposed. As the chaotic system is highly sensitive to its initial input, it is selected to encrypt the watermark image so as to enhance the security of the watermarking system, by modifying the size of m, the capacity of the watermark is variable, by modifying the power of embedding watermark, the robustness is variable. As the points in the engineering graphics are capable of tolerating a certain degree of change, stronger watermark energy can be embedded into these points. Experimental results show that the algorithm is robust against some processing operations, such as scaling, translation, rotation, adding and deleting.The other watermarking algorithm is a blind watermarking algorithm based on the entity substitution and mean value of wavelet coefficients. With this watermarking method, firstly, the beelines are replaced with polylines, and then the coordinates of vertices in polylines are extracted to be transformed by 2D DWT in order to obtain the DWT coefficients. The mean value is obtained by averaging the DWT coefficients except the low-frequency coefficients and watermark is embedded into it. As demonstrated by experimental results, this watermarking method has the advantages of excellent invisibility, strong robustness, large embedding capacity and blind detection.The watermarking approaches proposed in this paper success in solving those problems, such as low embedding capacity, weak robustness and non-blind extraction et al. in the previous methods, and can thus be used for copyright protection of 2D engineering graphics.