Robust digital watermark algorithm based on OFDM-CDMA

Abstract

The invention relates to a robust digital watermark algorithm based on OFDM-CDMA. The robust digital watermark algorithm based on the OFDM-CDMA mainly includes an original watermark processing method and an embedded region and embedded point selecting method. The specific process includes the steps of a, an original watermark processing process which comprises watermark randomizing, OFDM coded modulation and CDMA coding; b, a watermark embedding process which comprises watermark embedded region and embedded position selecting; c, a watermark extracting process. By means of the robust digital watermark algorithm based on the OFDM-CDMA, under the condition of lower watermark redundancy, mean value and variance of error data caused by various attacks can be reduced effectively, distribution of watermark error energy tends to be centralized, influences of the various attacks on the overall watermark are reduced effectively, and robustness of the watermark is improved.

Description

technical field [0001] The invention relates to the field of signal processing, in particular to a robust digital watermark algorithm based on OFDM-CDMA. Background technique [0002] Robust digital watermarking, as an effective digital product copyright protection technology, has developed into an important branch of information hiding research. The process of robust digital watermarking to resist various malicious attacks is similar to the anti-jamming process of communication system. Therefore, various anti-jamming techniques in communication system can be applied to robust watermarking system to improve the watermark's ability to resist various attacks. Error correction coding, spread spectrum technology and CDMA (Code Division Multiple Access) technology in communication theory are all effective means to improve the anti-interference performance of the system, and have been widely used in watermarking systems. [0003] However, with the widespread application of digita...

AI Technical Summary

Problems solved by technology

This type of attack has a strong randomness, and the attack strength is unknown in advance, which has a great impact on the watermark, directly causing serious distortion of the extracted watermark or completely destroying the watermark.

[0004] In the face of such strong attacks, the existing traditional algorithms cannot solve it well

Since the performance of the spread spectrum watermark algorithm is limited by the length of the spread spectrum code, the longer the code length, the better the performance, and at the same time the transparency of the watermark will be greatly reduced. Even through the compromise algorithm, the performance is still unsatisfactory.

Although the watermark algorithm combined with error correction coding and CDMA technology can make up for some shortcomings of the CDMA algorithm, it will also increase the watermark redundancy and algorithm complexity, especially the attack intensity of the digital watermark is unknown, so it is possible that the more correct Wrong situation

It can be seen that the existing typical algorithms still have deficiencies in terms of technical ideas, and cannot solve the problem of robustness of watermarking well.

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