Document Watermarking via Intra-word Space Modification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for embedding and extracting digital watermarks in text documents are limited by their dependence on printing and scanning processes, lack of resistance to distortions, and limited information capacity, as well as the requirement for special equipment and visible marks, which are not suitable for all applications.
Innovation Solution
A method that embeds and extracts digital watermarks by modifying intra-word and inter-word spaces in text documents, using a location analysis module to identify and optimize spaces, encode messages into codewords, and modify document spaces without requiring the original document or special equipment, ensuring resilience to distortions and independence from printing and scanning technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visible marks such as barcodes are added to documents, then information can be easily embedded and decoded, but the watermark becomes noticeable to users and may not be acceptable for aesthetic reasons
Solution Approach 1:
The patent applies local quality by making different parts of the document have different properties: the watermark is embedded at the character level (local) and is invisible to human inspection, while the overall document maintains its normal appearance. The watermark modifies individual character representations rather than adding visible marks, achieving both detectability and aesthetic quality.
2Ease of manufacture
If imperceptible watermarks are embedded in text documents, then the document appearance is maintained, but the techniques require special printing processes or equipment that are not universally available
Solution Approach 1:
The patent applies self-service by using standard printing and scanning processes that are already universally available. The watermark is embedded in the digital document before printing, and the extraction process uses only the scanned image itself without requiring the original digital document or special equipment. The system serves itself using common infrastructure.
Solution Approach 2:
The patent achieves universality by making the watermarking technique compatible with standard printing and scanning processes used by any office equipment. The method works with both digital and printed documents, and the extraction process can handle various document formats and conditions, making it universally applicable without specialized equipment.
3Loss of information
If watermarks are embedded using existing methods, then information can be concealed in the document, but the watermarks are not resistant to distortions from printing and scanning processes
Solution Approach 1:
The patent applies beforehand cushioning by embedding redundancy in the watermark structure and using error correction coding before the document undergoes printing and scanning. The watermark is designed to withstand expected distortions, and the extraction process includes error correction to recover the original information even when the document is distorted.
Solution Approach 2:
The patent applies parameter changes by transforming the watermark into the frequency domain and embedding it in a way that makes it robust to spatial distortions. The watermark signal parameters are optimized to survive printing and scanning processes, and the extraction process adapts to the distorted document parameters to recover the original watermark.
4Measurement precision
If the original document is required for watermark extraction, then accurate recovery is possible, but the method cannot work with distorted copies or scanned versions of the document
Solution Approach 1:
The patent applies taking out by extracting the watermark information directly from the distorted or scanned document copy without requiring the original digital document. The method separates the watermark extraction process from the need for the original file, allowing recovery from any document version including distorted copies and images.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A method for watermarking documents comprising: - identifying and locating spaces in a received original document (10) by a location analysis (110) module which distinguishes between intra-word spaces and inter-word spaces; - minimizing an error probability of interference between intra-word spaces and inter-word spaces in the watermarked document (20) by an optimization module (111); - encoding (113) the message (30) into codewords and encoding (114) the codewords into the watermark; embedding the watermark to generate (115) the watermarked document (20) by modifying the intra-word spaces and inter-word spaces of the original document (10).