ABSTRACT
The advent of the Internet and the wide availability of computers, scanners and printers make digital data acquisition, exchange and transmission a simple task. However, making digital data accessible to others through networks also creates opportunities for malicious parties to make salable copies of copyrighted content without permission of the content owner. Digital watermarking has been proposed as a solution to the problem of copyright protection of multimedia documents in networked environments. It makes possible to embed a watermark (such as identification data, serials number, text or image etc) to multimedia documents allowing copyright protection, secret communication, document authentication and so on.
In this paper, a wavelet transform based digital image watermarking blind scheme has been proposed. A wavelet transform to vector images first. Taking into account that only high-frequency components the details of the image texture and low-frequency section contains images most energy, to choice of high-frequency components CH, CV for embedding watermark, in order to guarantee the watermark image is visible. Apply the spread spectrum technology to complete this scheme. It is not embedded watermark sequence itself, but the random sequence according to a KEY. Through calculation of the correlation, it is successful to extract the watermark algorithm blind when there are not original vector images.
After the successful implementation of the watermark embedding and extraction of the embedded watermark image, the following attack experiments have been done: compression, tailoring, increase noise, rotation, and calculated from the original watermark and the watermark relevance. The experimental results confirmed that this blind scheme is robust to a variety of attacks such as, the compression, the tailors, Gauss noise.
KEY WORDS: digital watermarking, wavelet transform, spread spectrum technology
