A robust approach to stereoscopic 3-D video watermarking using adaptive hysteresis noise gate
Creators: name: AL-BORIDI, Omar
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 400607
subject: Signal processing
classificationCode: 460401
subject: Cryptography

description: The intellectual property (IP) protection of three-dimensional (3-D) media is a prominent issue for both academic and wider communities to combat the illegal distribution and pirating of this visual medium. Digital watermarking has been used to address various challenges in media IP protection. The challenge central to 3-D video as well as other audio-visual signal watermarking is that given a fixed level of perceptual transparency, a watermarking system cannot simultaneously achieve a high degree of robustness and a high watermark payload. Most published research in this field attempts to introduce new embedding methodologies to increase the watermark robustness while still providing the highest possible visual media quality.

This research aims to introduce an alternative approach to watermarking stereoscopic three-dimensional (S3-D) video using a dual-tree complex wavelet transform (DT-CWT) with an adaptive hysteresis noise gate or NG-DCWT for short. The DT-CWT has demonstrated superior performance in video watermarking when compared with direct spatial watermark embedding techniques, as well as other traditional frequency-based approaches. In frequency-based approaches such as the Fourier transform, the discrete cosine transform, and the discrete wavelet transform, the watermark is embedded in either low or high-frequency coefficients/components.
 
However, the approach proposed in this dissertation adopts a modified noise visibility function (NVF) as an on-off noise gate (NG) to capture areas of high activity more effectively in each video frame for watermark embedding. To enhance performance in terms of watermark invisibility and robustness, the modified NVF devised here detects regions of high spatial activity and frequency which statistically coincide with strong edge areas in the frame where the modulated watermark is embedded in each DT-CWT coefficient of the two chrominance (CB, CR) channels depending on its magnitude in the context of its neighbourhood. 
There were 46 (with left and right views ) full HD S3-D videos used in this research to test the watermarking algorithm, and both non-subjective and subjective performance evaluation was conducted.

General image processing and dedicated watermark removing attacks were considered, including cropping, downscaling and upscaling, Gaussian noise, geometric attack, watermark estimation re-modulation, temporal frame averaging, and multiple watermarks embedding attack. Mean opinion score (MOS) analyses were conducted based on the subjective test data, showing that the proposed algorithm visually hides the watermark in stereoscopic 3-D video effectively, while still maintaining comparable or better performance to or than that of the other state-of-the-art techniques reported recently in the literature, in terms of the false-negative ratio (FNR) and the true positive ratio (TPR). TPR analysis shows a sensitivity value of 98.93% achieved by the new algorithm, true negative rate (TNR) was 89.13% and the miss rate or false positive rate (FPR) was 1.08% which are comparable to that reported in the public domain using existing techniques.

Multi-criteria decision making (MCDM) with analytic hierarchy process (AHP) and Vikor was used to provide a ranking solution for determining the best means of ranking the quantitative solution. As seen previously, the four alternatives were as follows: downs factor FNR, proposed FNR, Asikuzzaman, et al. FNR, and Kim FNR. All available criteria (Gaussian noise, rotation, upscaling, and cropping(%)) were used for the four alternatives. Results indicated that the gaussian noise provides the best means of ranking the solutions.

Included among the targets in this research was to determine an optimal watermark load that leads to the minimal visible difference between the watermarked S3-D video and its original counterpart. The best performance watermark load was found to be 512kbs, however, the method of embedding the watermark in one of the two views with loads of 1024kbs and 2048kbs showed better performance than embedding the watermark in both views. The results of subjective testing indicated that the best watermark load is 512kbs in terms of visual quality.