ABSTRACT
The availability of versatile multimedia processing software and the far-reaching
coverage of the interconnected networks have facilitated flawless copying,
manipulations and distribution of the digital multimedia. However, abuses of these
facilities and technologies pose pressing threats to multimedia security management in
general. Digital watermarking, which could be used for a wide range of applications,
has become the focus of academic research.
The main focus of watermark research is to provide good tradeoff between
perceptual quality of the watermarked image and its robustness against different attacks.
For this purpose, adaptive watermarking algorithm has become the trend of the study. In
this paper, two robust adaptive watermarking schemes for color images based on
content are proposed. The main content as follows:
1. Presents a literature review of the existing watermarking techniques, mainly
focuses on adaptive watermarking algorithms;
2. Proposed a DWT domain adaptive watermark embedding method for color
image. The strength of embedding is calculated according to a series combination rule
that take into account contrast sensitivity characteristics of the HVS.HVS gives a direct
way to determine the maximum strength of watermark signal that each portion of an
image can tolerate without affecting the visual quality of the image.
3. Study the masking model of HVS in Contourlet domain, an adaptive watermark
embedding for color image is proposed based on the masking model. Simulation results
of various attacks are also presented to demonstrate the robustness of both the
algorithms. Simulation results verify theoretical observations and demonstrate the
feasibility of the digital watermarking algorithms for use in multimedia standards.
4. Use a binary image as the original watermark pattern. In order to improve the
robustness, use a two-phase coaxial holographic encryption method to encrypt the
watermark.
5. Study the performance of different color spaces in the embedding process. Test
results indicated that component in color space provided the best results
from the point of watermarked image quality and at the same time from the point of
watermark robustness against attacks.
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Key Word: Digital Watermarking, Color Image, Adaptive Watermark
Hologram Watermark, Color Space