Özet:

Due to the increased development in technique of data transfer over internet and transmission media, the access and copy to these data in unathentical manner became a big challenge in the transmission media. This challenge led to make effort in digital multimedia security. In this paper a new algorithm is proposed to protect image from unauthentication access using watermarking. The watermarking algorithm hide the mark image in frequency domain using Discrete Cosine Transform and extract it at the receiver from the transmitted image without need for origin image. The basic principle of the algorithm is depend on spread spectrum communications. The spread spectrum depend on transmit a narrow band signal over a much larger bandwidth where that the signal energy is undetectable. Similarly, the watermark image bits are spread by a large factor called chip-rate so that it is imperceptible and arrange in cover image in away where if the half of the watermarked image is cropped, the watermark image is not affected. The proposed algorithm efficiency is measured by using many of measurement factors such as Peak Signal to Noise Ratio PSNR and Normalized Correlation Coefficient NC, the watermark robustness and feasibility are measured by using many types of attacks.

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