The copyrights protection by using watermarks on image files

The developments in internet technology, publishing sector, electronic storage and broadcast have yield new research areas for researchers. One of these fields is watermarking technology. Many successfully researches on watermark technology have been done for ownership verification and copyright on multimedia files in last decade. The studies are still lasting to improve existing watermarking technologies. In this thesis, most commonly used watermark technologies are examined and tried to be improved. Two new contributions are made for existing technology. The first is the compound of LSB and DWT by using best properties of each watermarking technique. In this proposed method, the advantage of speed performance criteria of the LSB is combined with the robustness of the DWT. Good results are obtained especially where the speed is very important as in online broadcasting. The other is the improving of imperceptibility criteria. This is done on Digital Cosine Transform DCT which can embed watermark with minimum modification. An improvement is made on DCT using genetic algorithm to determine least significant DCT block. The watermark is embedded in this least significant block. This will be very effective in communication and cryptography where imperceptibility is very important. The two proposed techniques are tested with the performance criteria and good results are obtained. Keywords: Cryptography, Digital Watermark, Digital Signature, Copyrights, Wavelet.