Document Watermarking via Page Analysis and Multi-Scheme Embedding
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Solution Overview
Problem
Digital watermarking schemes for electronic documents with primarily textual images are unsuitable due to the low-bit color space, making it difficult to invisibly encode information and easier for malicious users to identify and remove watermarks.
Innovation Solution
A computer-implemented method and system that analyzes document pages to determine suitable watermarking schemes, embeds a unique identifier across multiple pages using error correction codes, and employs multiple watermarking techniques such as page element shifting, flyspecking, and text warping to securely associate the document with a user, discouraging unauthorized distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If traditional digital watermarking schemes are used on electronic documents with textual images, then ownership information can be encoded, but the low-bit color space makes it difficult to encode information invisibly and easier for malicious users to identify and remove watermarks
Solution Approach 1:
The patent changes the parameter space for watermark embedding by transitioning from color-based encoding to position-based encoding. Specifically, it modifies the spatial arrangement of text elements (such as shifting character positions, adjusting line spacing, or repositioning text blocks) to encode watermark information, thereby overcoming the limitations of low-bit color spaces in textual images.
Solution Approach 2:
The patent applies different watermarking techniques to different regions or elements within the document. By analyzing individual pages and selecting appropriate watermarking schemes for each, the system optimizes the embedding process for local characteristics of textual images while maintaining overall document integrity and watermark security.
2Reliability
If multiple watermarking schemes are analyzed and selected for different pages, then watermark robustness is improved, but the complexity of the watermarking system increases
Solution Approach 1:
The patent divides the document into multiple pages and analyzes each page individually to determine the most suitable watermarking scheme for that specific page. This segmentation allows the system to apply simplified, page-specific watermarking rules rather than requiring a complex unified approach for the entire document, thereby reducing overall system complexity while maintaining robustness.
Solution Approach 2:
The patent performs preliminary analysis of document pages before applying watermarking, categorizing pages by their suitability for different watermarking schemes. This pre-analysis creates a roadmap for watermark embedding that simplifies the actual watermarking process and reduces real-time computational complexity during document processing.
Data Source
AI summary
A watermark is embedded in a document having a plurality of pages. The pages of the document are analyzed to produce watermark information, which indicates whether the page is suitable for use with one or more of a plurality of watermarking schemes. The plurality of watermarking schemes may include page element shifting, flyspecking and text warping. An identifier (ID) is established, the ID associating the document with a user receiving the document. The ID is embedded in the pages of the document using the plurality of watermark schemes according to the watermark information. To recover an ID from a document, the pages of the document are analyzed to identify watermark information associated with the document. Embedded watermarks are recovered from the pages using the watermark information.