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| Identifier |
uch.csd.msc//2003mavrikakis |
| Title |
Χρήση ψηφιακών υδατογραφημάτων μεεφαρμογές στην προστασία εικόνων |
| Alternative Title |
Digital Watermarking aplied for Digital Image Protection |
| Creator |
Mavrikakis, Ioannis E
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| Abstract |
The gradual development of internet in most of the daily actions of people has lead the scientific and research community to find more inteligent and effective algorithms for managing the stored digital information. A requirement that must be satisfied for effective use of internet and the stored digital information is the protection of information which is trasmitted through the internet. The scientific area of multimedia is related closely with the internet. Daily a huge volume of digital data is trasmitted through it. The digital art must be protected from destructive attacks and from non legal commercial bussiness.The artists force the world of computer scientists to find rules that will protect their mentally and morally rights. Technical reasons also force us to reduce the non-limited transmissions and downloads of data through the internet. The old technology telecommunications networks can not stand up to the current increasingly requirements of bandwidth. So the constraints to the large databases of multimedia data by protection rules will reduce the transmision rate to a level which will serve all the users of the global network. At the project we have been centered into the digital image protection. Based on the theorem of Shannon we computed the capacity of the image or the capacity of subimages which is subdivided. Then we present the CDMA technique which is used for the insertion of watermark to the digital image. We also present the Discrete Fourier Transform (DFT) and we explore the advantages which has under specific attacks. Then we present the Discrete Cosine Transform (DCT) exploring out its inadequaties under specific attacks. On the other hand the use of discrete wavelet transform (DWT) in combination with the human vision system (HVS) solve a large number of attacks. An improvement to the performance of the previous algorithm we may have after the use of specific constraints at the way we insert the digital watermark. This constraints help us to maintain into the bandwidth which have been determined by the JND thresholds. From these implementations we conduct some experiments based on compression quality, on smoothing with Gauss Filters and finally some experiments joint the compression and soothing with Gauss Filter. We also implement a technique which is based on the content of the image. Our purpose with this technique was to face up geometric attacks such us rotation. Lastly we presented a compression technique which is based on wavelet transform for a unified purpose of compression experiments.
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| Issue date |
2003-04-01 |
| Date available |
2003-06-24 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Computer Science--Post-graduate theses
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Type of Work--Post-graduate theses
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| Views |
321 |
Χρήση ψηφιακών υδατογραφημάτων μεεφαρμογές στην προστασία εικόνων
