Multi-Level Document Authentication via Hierarchical Segmentation
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Solution Overview
Problem
Conventional pixel-based alteration detection methods for documents are computationally intensive due to high spatial resolution, making them inefficient for authenticating scanned documents compared to their original digital versions.
Innovation Solution
A multi-level image comparison method that segments documents into block, line, word, and character units, comparing these hierarchical structures to detect alterations, allowing for progressive and efficient authentication by stopping at the first detected alteration level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel-by-pixel image comparison is performed to detect alterations, then measurement precision is improved, but computational complexity increases
Solution Approach 1:
The patent segments the document image into hierarchical units (blocks, lines, words, characters) and performs comparison at multiple levels. Instead of comparing all pixels exhaustively, the system first compares block-level features, then line-level features, and finally character-level features only where needed. This segmentation approach maintains high measurement precision for alteration detection while significantly reducing computational complexity by avoiding unnecessary pixel-by-pixel comparison of entire documents.
2Measurement precision
If high spatial resolution scanning is used to capture document details, then measurement precision is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary extraction of hierarchical features (blocks, lines, words, characters) from the scanned document image before the actual comparison process. By pre-processing the image to identify and segment these structural elements, the system prepares the data in advance for efficient comparison. This preliminary action allows the authentication process to work with pre-segmented features rather than raw pixels, reducing processing time while maintaining the precision benefits of high-resolution scanning.
3Reliability
If exhaustive image comparison is performed to ensure authentication accuracy, then reliability is improved, but productivity decreases
Solution Approach 1:
The patent implements a multi-level comparison strategy where the system performs partial comparisons at each hierarchical level. It compares block-level features first, and only proceeds to line-level and character-level comparisons for blocks that show differences or are suspected of containing alterations. This partial action approach maintains high authentication reliability by thoroughly examining suspicious areas while improving productivity by avoiding exhaustive comparison of entire documents that are likely authentic.
Data Source
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AI summary
A document authentication method compares a target document image (scanned image) with an original document image at multiple levels, such as block (e.g. paragraph, graphics, image ), line, word and character levels. The paragraph level comparison determines whether the target and original images have the same number of paragraphs and whether the paragraphs have the same sizes and locations; the line level comparison determines if the target and original images have the same number of lines and whether the lines have the same sizes and locations; etc. Document segmentation is performed on the target and original images to segment them into paragraph units, line units, etc. for purposes of the comparisons. The original document may be segmented beforehand and the segmentation information stored for later use. The authentication process may be designed to stop when alterations are detected at a higher level, so lower level comparisons are not carried out.