Research On High Reliability Encoding And Decoding Technology Of Printing-Quantum-Dots

The use of halftone single dot(referred to as printing-quantum-dots)dot matrix images to realize information hiding and printing information anti-counterfeiting has the advantages of large information recording capacity,good hiding effect and full coverage,and has become a research hotspot in the field of printed information anti-counterfeiting.However,in the process of information printing and recording,this method often has serious errors due to unavoidable defects such as missing printing,offset,dot enlargement,and flying ink,as well as the influence of illumination,shooting action jitter and other factors on the reading equipment.Therefore,its research has important application value.In view of the above problems,this thesis proposes an information hiding and information reading algorithm for printing-quantum-dots based on multiple combination encoding and decoding.Firstly,the printing-quantum-dots image generation algorithm encrypts the item coding information(such as anti-counterfeiting marks,website,serial numbers,text or trademarks,etc.),and then uses the multiple combined channel reliability coding method to solve the sudden bit error and random bit error in the printing and reading process of ciphertext information.In the multiple combined coding scheme,BCH codes,Hamming codes,convolutional codes,Turbo codes and LDPC codes + interleaving coding are used to generate the original image of printing-quantum-dots and conduct comparative studies.At the same time,in order to realize the effect of full implantation and solve the blind reading and pseudo-random information hiding effect,the synchronization information of Barker code is added to dot matrix information of original image.Secondly,in order to match the size of cover image when the information is implanted,the original image of dot matrix is copied and spliced,and the pseudo-random scrambling method is used to solve the moire problem caused by the dot matrix arrangement rules of the spliced image.Finally,the printing-quantum-dots image is obtained through spatial information modulation.The block reading algorithm is adopted for the information reading of printing-quantum-dots.First,the sampled printing-quantum-dots image is demodulated and descrambled,and then the dot matrix image block containing the complete secret information is quickly found according to the synchronization information.Then BCH decoding,Hamming decoding,Viterbi decoding,turbo decoding and LDPC decoding + deinterleaving are selected according to the coding scheme,and finally the plaintext information is read out through decryption.The information reading time of printing-quantum-dots with different algorithms and the reading situation under different bit error rates are compared experimentally.At the same time,the image quality evaluation indexes PSNR and SSIM are used to evaluate the information hiding quality.The experimental results show that the information hiding algorithm of printing-quantum-dots based on multiple combination encoding and decoding has better error detection and correction ability,information hiding quality and faster reading rate.The algorithm in this thesis generates the printing-quantum-dots image by cross-application of reliable channel coding in modern communication systems,interleaving coding,halftone screening,information encryption,pseudo-random scrambling,digital image recognition and other technologies.It can not only make the dot matrix information by using the characteristics of unit printed ink dots(space vector distribution,shape and size),but also solve the problem of bit error.This technology can be well applied to copyright protection of printed matter,preventing counterfeiting and infringement,and improving information value-added services.