Inter-word Space Modulation for Robust Text Data Hiding

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Solution Overview

Problem

Existing methods for hiding data in text documents face challenges due to visual artifacts and distortion from processes like photocopying, printing, and scanning, making it difficult to retrieve hidden information without the original document, and have limited data embedding capacity.

Innovation Solution

The method employs inter-word space modulation by dividing inter-word spaces in a text row into two sets and modifying their lengths to embed data, ensuring the total length remains constant and minimizing visual distortion, allowing for robust data hiding and extraction even after document distortions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If pixel values are modified to embed data in text documents, then data embedding capacity is achieved, but visual artifacts (salt-and-pepper noise) are introduced

Engineering Contradiction:

Improvedata embedding capacityVSAvoidvisual artifacts

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent changes the parameter being modified from pixel values to inter-word space lengths. Instead of flipping individual pixels (which causes visual artifacts), the method adjusts the length of spaces between words, which is imperceptible to human vision. This parameter substitution allows data embedding without introducing visible noise while maintaining embedding capacity.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If document distortion occurs from photocopying, printing, and scanning, then data retrieval becomes difficult without original document, but existing methods still embed data

Engineering Contradiction:

Improvedata embedding capacityVSAvoiddata retrieval robustness

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies preliminary error correction coding (such as Reed-Solomon or convolutional codes) to the data before embedding it into inter-word spaces. This preliminary action ensures that even if some space length measurements are distorted during photocopying, printing, or scanning, the original data can be reliably recovered through the error correction mechanism without needing the original document.

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If inter-word space lengths are modified to embed data, then data embedding capacity increases, but document distortion may affect measurement accuracy

Engineering Contradiction:

Improvedata embedding capacityVSAvoidinter-word space measurement accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent employs feedback mechanisms where the system measures the actual inter-word space lengths after document processing, compares them against expected values, and uses error correction decoding to compensate for measurement errors. This feedback loop ensures that even when distortion affects measurement precision, the embedded data can be accurately recovered by detecting the intended space length modifications despite the noise.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7724916B2System and method for data hiding using inter-word space modulation

Publication Date: 2010.05.25 NEW JERSEY INSTITUTE OF TECHNOLOGY

AI summary

Data may be embedded in rows of text by modulating inter-word spaces in a row. Inter-word spaces in a particular row may be divided into two or more sets of (approximately) equal spacing. The inter-word spaces of one or more of the sets may then be modified to embed data.