Reversible Watermarking for Image Restoration and Access Control
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Solution Overview
Problem
Existing digital watermarking techniques fail to efficiently restore an image to its pristine state after watermark removal, especially when multiple watermarks are applied, and do not effectively manage image degradation for different consumer access levels.
Innovation Solution
The use of a combination of robust and reversible watermarks, where the robust watermark survives image corruptions and the reversible watermark allows complete removal of encoding artifacts, enabling restoration of the image to its original state and allowing different consumers to access varying levels of image quality based on authorization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single robust watermark is used, then the watermark survives image corruptions and manipulations, but the image cannot be completely restored to its original state
Solution Approach 1:
The patent divides the watermarking function into two separate watermarks: a robust watermark that survives corruptions and a reversible watermark that enables complete restoration. This segmentation allows each watermark to specialize in one function, resolving the contradiction between robustness and restorability.
Solution Approach 2:
The patent combines two watermarks (robust and reversible) into a single watermarked image. The reversible watermark contains embedding information that, when removed, restores the original image. This merging allows both robustness and complete restoration to coexist in the same system.
2Adaptability or versatility
If multiple watermarks are applied to provide different access levels, then consumer authorization control is improved, but the complexity of watermark management increases
Solution Approach 1:
The patent segments different access levels into separate reversible watermarks, each containing information about the degradation level. This allows multiple consumer classes to be managed through distinct watermark types while maintaining a consistent overall structure, reducing management complexity.
Solution Approach 2:
The patent uses different degradation parameters (levels of degradation) to distinguish between consumer access levels. By varying the degradation parameter rather than creating entirely different watermark systems, the patent achieves adaptability while controlling complexity.
3Reliability
If image degradation is applied to control access levels, then security against unauthorized access is improved, but the image quality for authorized users may be compromised
Solution Approach 1:
Instead of degrading the image to protect it, the patent embeds watermarks that can reverse the degradation. The reversible watermark contains information to restore the original image quality, so the degradation is temporary and controllable rather than permanent, resolving the contradiction between security and quality.
Data Source
AI summary
The ability to remove a watermark from an encoded image by reversible watermarking opens the possibility of various novel applications. Several such applications are detailed. One permits different classes of consumers to gain access to different versions of an image. A pristine image is intentionally degraded in some fashion, and distributed to consumers. By reference to one or more watermarks in the degraded image, some or all of the degradation can be removed, or transformed to a less-objectionable state. Through such arrangements, image consumers with different needs can gain access to versions of the image having differing qualities.