Recoverable Video Watermarking via DCT DC Coefficient LSB Embedding
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Solution Overview
Problem
Current digital watermarking technologies fail to survive block-based image and video compression techniques, leading to the destruction of the watermark, which restricts their application in video transmission networks that require compression, such as satellite TV or video-over-DSL.
Innovation Solution
Embedding a recoverable watermark by using one or more of the lowest order bits of the discrete cosine transformation (DCT) coefficient, which is retained unmodified through the encoding and decoding process, allowing the watermark to survive multiple transcodings and compression processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current digital watermarking technologies are used, then watermark embedding is achieved, but the watermark is destroyed by block-based compression techniques
Solution Approach 1:
The invention extracts and utilizes the least significant bits (LSBs) of the DC coefficients, which are naturally retained during compression. By embedding watermark data in these specific bits that are preserved by the compression algorithm, the watermark survives the compression process while the visual quality remains unaffected.
Solution Approach 2:
The invention changes the parameter being modified from significant image data to the least significant bits of DC coefficients. This parameter change allows watermark embedding that is invisible to the human eye yet resilient to compression, as these LSBs are preserved during the compression process.
2Productivity
If block-based compression is applied to reduce data size, then compression efficiency is improved, but watermark information is lost
Solution Approach 1:
The method extracts and utilizes the least significant bits of the DC coefficients, which are naturally retained during compression. By embedding watermark data in these specific bits that are preserved by the compression algorithm, the watermark survives the compression process while maintaining compression efficiency.
Solution Approach 2:
The least significant bits of DC coefficients serve as an intermediary carrier that bridges the compression process and watermark preservation. These bits act as a hidden channel that is unaffected by compression operations, allowing both compression and watermarking to coexist.
3Difficulty of detecting and measuring
If watermark is embedded in visible signal components, then watermark detectability is improved, but visual quality degradation occurs
Solution Approach 1:
The invention applies local quality modification by embedding watermark data only in the least significant bits of DC coefficients, which are imperceptible to human vision. This localized approach to embedding ensures that the watermark is detectable through algorithmic analysis while causing no visible degradation to the image quality.
Solution Approach 2:
The method effectively changes the 'color' or properties of the watermark embedding from visible modifications to invisible bit-level changes. By operating at the bit level in the least significant positions, the watermark becomes undetectable to human vision while remaining recoverable through digital analysis.
Data Source
AI summary
A method for performing recoverable image and video watermarking which survives the use of block-based image and video compression techniques. One or more of the lowest order bits of the first DCT coefficient (the “DC” coefficient) which is to be coded are used as a “data channel” by which information representing a recoverable watermark may be embedded into an image or into a video signal frame. Encoding is performed by replacing one or more low order bits of the luminance value of each pixel in a block with a number of bits of the watermark data, and decoding is performed by averaging one or more low order bits of the decoded luminance values of the pixels in a block to retrieve a corresponding number of bits of the watermark data.