Video Watermark Embedding in Frequency Domain for Robust Extraction
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Solution Overview
Problem
Existing digital watermarking methods, particularly spatial-domain least significant bit watermarking, are not robust and struggle to effectively extract watermarks under compression, re-encoding, and other attacks.
Innovation Solution
Perform time-frequency transformation on video frames to embed watermark data in frequency domain coefficients, followed by inverse transformation to synthesize watermarked video, leveraging the position invariance and linear transformation characteristics of frequency domain signals to enhance robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spatial-domain least significant bit watermarking method is used, then watermark embedding is simple and color change is minimal, but robustness is poor and watermark extraction is difficult under compression and re-encoding
Solution Approach 1:
The patent transforms the watermark embedding approach from spatial domain to frequency domain by applying discrete cosine transform (DCT). Instead of modifying least significant bits of pixel values, the method embeds watermark information in frequency domain coefficients after DCT transformation. This parameter change in the domain of operation fundamentally improves robustness against compression and re-encoding while maintaining embedding simplicity through systematic coefficient modification.
Solution Approach 2:
The patent replaces the mechanical bit-manipulation approach of spatial domain watermarking with a mathematical transformation approach using DCT. By substituting direct pixel value modification with frequency domain transformation and coefficient embedding, the system achieves superior robustness. The mathematical properties of DCT (energy concentration, reversibility) provide inherent protection against common signal processing attacks.
2Reliability
If frequency domain watermarking is applied, then robustness against compression and re-encoding is improved, but computational complexity increases due to time-frequency transformation
Solution Approach 1:
The patent employs discrete cosine transform (DCT) as the specific time-frequency transformation method. DCT is chosen because it concentrates signal energy into fewer coefficients (energy compaction property), allowing efficient watermark embedding in a compact representation. The transform is reversible and computationally efficient compared to other transforms like Fourier transform, thus achieving robustness while controlling computational complexity through algorithmic optimization.
3Reliability
If watermark data is embedded in multiple image frames, then robustness against attacks is enhanced through majority voting, but processing time and computational load increase
Solution Approach 1:
The patent divides the video watermarking task into independent frame-level operations. Each image frame is processed separately through DCT, watermark embedding, and inverse DCT. This segmentation allows parallel processing of multiple frames and enables the majority voting mechanism to work efficiently by comparing results from individual frame extractions. The independent frame processing reduces overall computational load compared to processing the entire video as a single unit.
Data Source
AI summary
Disclosed in this application are a method for embedding a watermark in video data and apparatus, a method for extracting a watermark in video data and apparatus, a device, and a storage medium. The method for embedding the watermark includes: acquiring a target image frame in video data; performing time-frequency transformation on the target image frame to obtain target frequency domain data, the target frequency domain data comprising a matrix formed by frequency domain coefficients; changing the frequency domain coefficients in the target frequency domain data according to watermark data to obtain watermarked frequency domain data; performing inverse time-frequency transformation on the watermarked frequency domain data to obtain a watermarked image frame; and synthesizing watermarked video data according to the watermarked image frame.