Watermark Extraction via Pre-Distorted Synchronization Templates
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Solution Overview
Problem
Existing watermarking systems face challenges in balancing transparency, robustness, security, and processing load, particularly in detecting watermarks from distorted content while minimizing false positive detections and computational resources.
Innovation Solution
The method involves generating pre-distorted synchronization templates by distorting pilot contents with various distortions and selecting templates that match received synchronization portions, allowing for efficient evaluation of watermark frames and extraction of watermarks with reduced false detection probabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If watermark detection uses traditional synchronization template matching, then the system is simple to implement, but the false positive rate increases and detection reliability decreases when content is distorted
Solution Approach 1:
The system pre-generates multiple distorted synchronization templates before actual watermark detection occurs. These templates are created by applying various distortion operations (scaling, rotation, cropping, filtering) to the original synchronization template in advance, so that when distorted content is detected, the matching process can immediately use the pre-prepared templates without real-time distortion analysis.
Solution Approach 2:
The system changes the parameters of synchronization templates by generating multiple versions with different distortion parameters (scale factors, rotation angles, crop regions, filter types). This allows the detection system to match against templates that already account for various possible distortions, improving reliability without requiring complex real-time parameter estimation.
2Measurement precision
If the system generates and compares against multiple pre-distorted synchronization templates, then detection accuracy improves, but processing load and computational resources increase
Solution Approach 1:
The synchronization detection process is segmented into two distinct phases: an offline phase where multiple pre-distorted templates are generated and stored, and an online phase where only simple matching operations are performed. This segmentation moves the computationally intensive template generation to when processing is not time-critical, while keeping the actual watermark extraction process fast and efficient.
Solution Approach 2:
The computationally expensive operations of generating distorted templates through various transformations (scaling, rotation, filtering) are performed in advance and stored for later use. During actual watermark extraction, the system only performs lightweight correlation operations between the extracted synchronization signal and the pre-generated templates, significantly reducing processing time.
3Adaptability or versatility
If the watermark synchronization template is designed to be robust against distortions, then the watermark becomes more detectable in distorted content, but the template size and complexity increase
Solution Approach 1:
Instead of designing a single complex template that attempts to handle all distortions, the system creates multiple copies of the original synchronization template, each copy being transformed with specific distortion parameters. This allows the system to maintain simple, clean template structures while achieving broad distortion coverage through the collection of transformed copies.
Solution Approach 2:
The system achieves distortion tolerance by changing the parameters of multiple template copies (scale, rotation, crop, filtering) rather than modifying the fundamental structure of a single template. Each template copy remains structurally simple and easy to generate, but the collection as a whole provides comprehensive coverage of possible distortions.
4Reliability
If the system performs exhaustive search over all possible distortion variations, then detection robustness maximizes, but processing time and computational complexity become unacceptable
Solution Approach 1:
The system performs a partial search over the distortion space by selecting and generating only the most likely distortion variations based on expected real-world transformations. Rather than exhaustively searching all possible distortions, the system focuses computational resources on the subset of distortions that are most probable in practical scenarios, achieving good detection robustness with acceptable processing time.
Solution Approach 2:
The system pre-generates aĉé set of distorted templates covering the most common distortion types and ranges before actual watermark detection. This preliminary action allows the system to achieve robust detection without performing exhaustive real-time searches, as the templates are prepared in advance when computational resources are more readily available.
Data Source
AI summary
Methods, devices and computer program products facilitate the extraction of embedded watermarks in the presence of content distortions. Subsequent to the detection of a tentative watermark, particular sections of the content are examined to form one or more extrapolated watermarks or watermark segments. Weights are assigned to the extrapolated watermarks or watermark segments, and used in combination with the detected tentative watermark to collectively assess if a desired probability of false detection is satisfied.