Encryption And Watermarking Technology Of Digital Image

The rapid growth of the IT(Information Technology) makes electronic mediacommunication easier and more extensive than before. While this enables the illegalcreation and dissemination of products quickly via electronic means. There haveemerged many techniques for protecting the security of multimedia information inrecent years. Image digital encryption and watermark is a booming technique, which,in fact, is information hiding technique using in image processing field.Based on the advanced achievement in this field, this thesis discusses mainly theencryption and watermark technology in the security of digital image by usingmathematics, cryptography, information theory etc. Firstly it explains the background,development, current situation and application of the digital image encryption andwatermark technologies, then expound the principle, characteristics, classification andtypical algorithms respectively.Subsequently, when studying these typical algorithms, point out the deficiencyand raise improved algorithms:1. Traditional image encryption techniques basing FFT transform confuse thephase of the original image to encrypt. When using the same secret key encryptsseveral images, the information in original image can be separated by IndependentComponent Analysis (ICA). The security doesn't very well. In this article, proposed amethod called phase modulation which solves the problem favourably.2. Study a new encryption algorithm—image encryption basing MOJETTEtransformation. This algorithm mainly uses the characteristic that MOJETTEtransformation produces lots of redundancies to encrypt image. There is littleliterature about it. The illumination of the algorithm isn't detailed and the values ofparameters are exceptive in the scanty literatures. So propose a new numericalalgorithm with ecumenical values of parameters to illustrate.3. Study digital image watermarking technique in DCT domain. Thereinto,visible watermarking technique based on luminance and texture features determine the depth of watermark insertion by luminance and texture features. But the algorithmof insertion depth is rough, also doesn't explain how to take the threshold value. Inthis article, propose an improved algorithm which uses Border detecting technique toinsert the watermark to original image subtly, in order to improve Robustness andoptic- balance.Digital image encryption and watermarking domain is hotspot of study whichcomes down to several disciplines such as digital image processing, communicationtheory, and encryption. At present, the study in these fields especially in digitalwatermarking is even in immature stage. More study task will be continued.