Research On Digital Watermarking Technology Of Engineering Graphics For Practicability

As the traditional industries such as machinery manufacturing, architecturalengineering and costume design gradually go toward the network, computer aideddesign has been widely used, which brings engineering graphics that exist in the formof digital multimedia various potential safety hazards. Because of its reliablecopyright protection and content authentication scheme, the technology of digitalwatermarking for engineering graphics has attracted extensive attention. Designing aneffective and practical watermarking algorithm, besides considering thecharacteristics of graphics and choosing a suitable watermarking type, the practicalapplication is also needed to be satisfied to make the algorithm on balance intransparency, security and practicability.Based on researches on existing watermarking technology of vector graphics,two watermarking schemes of engineering graphics for data robustness and integrityare proposed in this paper. Meanwhile the application of schemes in digital rightmanagement (DRM) system is introduced.Firstly, a blind watermarking algorithm of engineering graphics for datarobustness is proposed. The vertexes are preprocessed and mapped to the affineinvariant space to obtain rotation, translation and scaling invariance; and Thenclassifies the information obtained and constructs small matrixes, after singular valuedecomposition, the watermarking information modulated by chaos will be embeddedinto singular values by odd-even quantization, the smaller the matrix is, the higher thecapacity is; Finally, the vertexes are inserted into lines to locate original orders andensure correct watermarking extraction. The experimental analysis show that theproposed algorithm has good transparency, larger watermarking capacity, and isrobust against attacks of geometry, addition, deletion, rearrangement, vertex reversal.Secondly, a selective authentication watermarking algorithm of engineeringgraphics for data integrity is proposed. First get the vertices and map them intolog-polar coordinates, the sum of amplitude before accuracy and handle of previousentity is used to generate a characteristic information; then use improved expansion algorithm (IDE) to embed watermarking into data of amplitude and phase afteraccuracy, in order to realize blind detection, the number of watermark is correspondto carriers’. Experimental analysis show that the proposed algorithm has goodtransparency, is robust against geometric operations that do not affect the normal useof graphics and is extremely sensitive to malicious attacks which can changing thegraphics’ contents, meanwhile it can realize tamper localization and the accuracy is asingle entity.Finally, the application of watermarking algorithm for engineering graphics indigital right management (DRM) system is introduced, and each function module isstated in detail, then technical implementations of key functions are illustrated.