Abstract
Watermark is the copy deterrence mechanism used in the multimedia signal that is to be protected from hacking and piracy such a way that it can later be extracted from the watermarked signal by the decoder. Watermarking can be used in various applications such as authentication, video indexing, copyright protection and access control. In this paper a new CDMA (Code Division Multiple Access) based robust watermarking algorithm using customized 8 × 8 Walsh Hadamard Transform, is proposed for the color images and detailed performance and robustness analysis have been performed. The paper studies in detail the effect of spreading code length, number of spreading codes and type of spreading codes on the performance of the watermarking system. Compared to the existing techniques the proposed scheme is computationally more efficient and consumes much less time for execution. Furthermore, the proposed scheme is robust and survives most of the common signal processing and geometric attacks.
Highlights
Now-a-days, internet and multimedia technologies have become part and parcel of the human life.The information shared on the world wide web is proliferating day by day
The transformation matrix of the Walsh Hadamard Transforms (WHT) consists of only value of 1 and −1 which directly implies that the calculation of Walsh Hadamard Transform of an image consists of
The color image to be watermarked is converted to YUV format and the watermark is embedded only in the Y plane based on the property of human visual system (HVS) which states that the human eye is more vulnerable to changes in the color component compared to that in the intensity component [9]
Summary
Now-a-days, internet and multimedia technologies have become part and parcel of the human life. The embedding algorithm should be designed in such a way that the embedded watermark survives the above mentioned attacks and can be extracted from the attacked image by the decoder. Such algorithms are known as robust and secure algorithms. Some researchers apply the concept of CDMA based communication system in which watermark will be spread using the orthogonal spreading code which is generated using the security key and is added to the selected frequency coefficients [7]. The additive noise and signal distortions in communication systems are similar compared with the unintentional manipulations on the image and malicious attacks in watermarking. Three different cover images and three different watermarks for analysis as shown in succeeding sections
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