Research On Digital Image Watermarking And Interrelated Technique

With the speedily development of digital technology and Internet, multimedia digital products in various forms (image, video, audio, etc) have been frequently published on the Internet. Meanwhile, the information security of the multimedia digital production is becoming more and more urgent. Two effective ways to solve the problem are encryption and digital watermarking technology. In this paper, a research on encryption and watermarking of digital image is done, which includes these follow three aspects:Firstly, a digital image encryption algorithm based on four-value chaotic array is proposed. It uses chaotic maps to generate a four-value chaotic array. The array size is as big as the image. In encryption processing, we deal with the different value in the chaotic separately. For each chaotic array value corresponding pixel point, we use different keys to encrypt its pixel, and then put the result into the position, which is confirmed by the chaotic array and the random integers. Decryption is the converse of encryption. The analysis and the results of experiments show that the scheme has low time complexity, low space complexity and good security.Secondly, a robust zero-watermarking algorithm based on chaotic array is improved, which constructs a chaotic array, and then uses the chaotic array to find out the "embedded" position. After getting the position, it compares the MSB(most significant bit) of the image with the watermarking information. It gets the last watermarking array by setting the values of the chaotic array based on the results of the comparison. The results of experiment show that the scheme has good performance in common intentional or unintentional attacks such as cropping, additive noise, multipliable noise, rotating, filtering, scaling, and JPEG compression.Thirdly, a novel fragile watermarking scheme based on SVD (Singular Value Decomposition) and chaotic mapping is proposed. It obtains chaotic initial values and control values from the image blocks singular value decomposition, user's key and blocks position information, then uses the chaotic maps to get the chaotic sequence and embeds the sequence into the LSBs of the image blocks to get the watered image blocks. At last, reconstruct the watermarked image from all the embedded blocks. Analysis and experimental results show that the scheme is very fragile to tampering, and it can localize the tampering localization very accurately, reach to 3×3 blocks.Finally, conclude this paper and present further research aspects of the image encryption and digital watermarking technologies.