Research On Anti-printing Scanning Digital Watermarking For Complex Layout Documents

The development of information technology has brought many benefits and conveniences to people,but the problems of information security and copyright protection have also become increasingly prominent.As an important means of information interaction,digital prints have been paid more and more attention to copyright protection and information security.Digital watermarking,as a research direction of information hiding,plays an important role in copyright protection and information hiding.This paper mainly researches and implements anti-printing scanning digital watermarking technology for text and image respectively.Based on this,the image and text segmentation technology of complex layout documents is further studied,so as to add anti-printing and scanning digital watermark to complex layout documents.Finally,the application of this solution to the dedicated printer consumable So C chip is forecasted.This paper focuses on the basic principles of text watermarking,and proposes a text watermarking algorithm that is resistant to printing-scanning and can embed large amounts of information.This method uses the mathematical hypothesis model of print scan transformation to obtain the invariants in the process of print-scan.The algorithm then uses the Fourier Descriptor to flip unimportant pixels with high-frequency information on the character boundary based on print-scan invariants.Next,based on the resolution of the print-scan instrument and its influence on the invariance of the print-scan,a quadratic quantization function is proposed to embed multi-bits watermark information into a single character.Finally,through the study of the QR code,due to its large information capacity,strong error correction capability,and high decoding reliability,embedding the QR code into the text through the watermark algorithm can reduce the error rate of watermark extraction and improve the robustness of watermark information.The experimental results show that the proposed text watermarking algorithm has the characteristics of anti-print scanning,anti-scaling,large capacity,and has good visual effects.Then this paper studies and implements a DWT-based image watermarking method which is anti-printing scanning.Firstly,the basic theory of wavelet transform is deduced.This paper analyzes the influence of the wavelet coefficients in the DWT transform of the image by the print-scan process,and concludes that the HH2 wavelet coefficients of the image can be used as the invariant of the print-scan to perform watermarking embed and extract.Finally,the experimental results show that the algorithm is robust and has characteristics such as anti-print scanning,anti-scaling,large capacity,and anti-shearing.Next,this paper implements a graphic segmentation scheme based on connected fields and mathematical morphology.Firstly,the basic theory of graphic segmentation is explained,and then the algorithm flow is described.Experimental results show that the scheme can correctly segment text and image parts,and then we can combine the text and image watermarking algorithms to provide a solution for adding digital watermarks to documents with complex layouts.Finally,combing the existing results and problems in this paper,the research directions and work that can be carried out in the next step are sorted out.