Chrominance Watermarking for High Bit Rate Video
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Solution Overview
Problem
Existing video watermarking techniques face limitations in bit rate due to human visual system sensitivity, particularly with luminance, and require multiple frames for accurate transmission, which can be disadvantageous in applications needing finer granularity and resistance to temporal tampering.
Innovation Solution
The method involves embedding watermark data in the chrominance component of video signals, specifically by modifying the average value of chrominance blocks on a per-frame basis, using techniques like block-based frequency domain encoding, and replicating data across frames to improve reliability and resistance to tampering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional information is encoded in the luminance component of the video signal, then the human visual system can perceive the watermark, but the bit rate is limited to below 120 bits per second due to sensitivity to distortion
Solution Approach 1:
The patent changes the parameter of the video component used for watermarking from luminance to chrominance. Specifically, it embeds additional information in the Cb and Cr components of the YCbCr color space, which are chrominance components. This parameter change allows achieving bit rates greater than 150 bits per second while maintaining imperceptibility to the human visual system, as the HSVS is much less sensitive to chrominance than luminance.
2Measurement precision
If multiple frames are used to transmit watermark data, then accurate transmission is achieved, but response time increases and resistance to temporal tampering decreases
Solution Approach 1:
The patent segments the watermarking process by applying watermarking to individual frames or even individual blocks within frames, rather than requiring multiple complete frames. This is achieved by embedding data in the chrominance components of each frame independently, allowing for finer granularity and faster response time while maintaining transmission accuracy through the use of error correction codes.
3Productivity
If chrominance component is modified to carry higher bit rate information, then bit rate increases beyond 120 bits per second, but distortion of chrominance component increases
Solution Approach 1:
The patent changes the parameter of the video component used for watermarking from luminance to chrominance. Specifically, it embeds additional information in the Cb and Cr components of the YCbCr color space, which are chrominance components. This parameter change allows achieving bit rates greater than 150 bits per second while maintaining imperceptibility to the human visual system, as the HSVS is much less sensitive to chrominance than luminance.
Solution Approach 2:
The patent uses error correction coding to create redundant copies of the watermark data. By encoding the additional information with error correction codes before embedding it in the chrominance components, the system can recover the original data even when some distortion occurs during compression or transmission, thus maintaining effective data quality despite chrominance distortion.
4Loss of time
If watermarking is applied on a per-frame basis with block-level granularity, then response time improves and resistance to temporal tampering increases, but complexity of watermarking process increases
Solution Approach 1:
The patent segments the watermarking process by applying watermarking to individual frames or even individual blocks within frames, rather than requiring multiple complete frames. This is achieved by embedding data in the chrominance components of each frame independently, allowing for finer granularity and faster response time while maintaining transmission accuracy through the use of error correction codes.
Data Source
AI summary
Data to be impressed upon the average value of a chrominance portion of a block, is replicated at least once. The original and each replica is impressed on blocks in the same block position of separate frames. The frames that have like-positioned blocks that are carrying the same data are considered to be a group. Specific blocks of the frame may be embedded with a particular known data sequence rather than user data. Each group may employ a different known sequence. Instead of simply repeating the data for each like-positioned block of a group, the amount added to the average value for each such block may be changed slightly from frame to frame in group, even when the complexity of the blocks is the same. At a receiver, the multiple instances of the same data bit are extracted and combined to form a single received bit.