IR Security Mark Tampering Detection via Pixel Density Analysis
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Solution Overview
Problem
Existing methods fail to accurately detect tampering of infrared (IR) security marks in documents, leading to potential misclassification of documents as non-confidential or non-genuine, especially when tampering occurs unintentionally or by mistake.
Innovation Solution
A method and system that involves scanning documents with IR security marks, segmenting the scanned data into blocks, calculating the ratio of white to black pixels, and comparing this ratio with a threshold to detect tampering, ensuring accurate classification of the document's authenticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional IR security mark detection methods are used, then document authentication is performed, but the detection fails when the IR security mark is tampered with (crumpled, written over, etc.), leading to false classification as non-genuine
Solution Approach 1:
The patent divides the scanned document into multiple image blocks and further segments each block into smaller pixel grids. This segmentation allows the system to analyze local pixel density characteristics in different regions, making the detection robust against partial tampering while maintaining overall system reliability without excessive complexity.
Solution Approach 2:
The patent applies different analysis approaches to different regions of the document. By calculating pixel density ratios locally in each image block and comparing against thresholds, the system adapts to local variations in the IR security mark while detecting anomalies. This local quality approach improves detection accuracy without requiring a completely complex global analysis system.
2Measurement precision
If the IR security mark is analyzed by extracting and recognizing embedded security texts/images, then genuine documents are identified, but the method becomes ineffective when tampering occurs, causing false negatives
Solution Approach 1:
The patent extracts pixel density information from each image block without requiring extraction of the embedded security texts or images. By taking out only the essential pixel density characteristics and analyzing these independently, the system can detect tampering even when the embedded security elements are obscured or damaged, thereby improving measurement precision while reducing detection difficulty.
Solution Approach 2:
The patent creates a simplified representation (copy) of the IR security mark by calculating pixel density ratios in grid blocks, rather than working with the complete original security text/image data. This copied representation maintains the essential verification characteristics while being more robust to tampering and easier to analyze, thus improving both precision and reducing measurement difficulty.
3Ease of manufacture
If simple security marks are used, then documents are easier to process, but they are easier to duplicate and counterfeit
Solution Approach 1:
The patent employs an asymmetric detection approach where the verification process is more complex than the mark itself, using pixel density ratio analysis and threshold comparisons. This allows simple IR security marks to be used in documents (maintaining ease of manufacture), while the asymmetric verification algorithm provides strong protection against counterfeiting by detecting even subtle tampering patterns that would be difficult to replicate.
Data Source
AI summary
The present disclosure discloses methods and systems for detecting tampering of an infrared (IR) security mark in a document. The method includes receiving the document including the IR security mark, wherein the IR security mark further includes one or more security texts and/or images. The document is scanned to generate scanned data. A portion of the scanned data including the IR security mark is segmented into a plurality of blocks such as blocks of size 32*32. Thereafter, a ratio of white to black pixels is calculated for each block. The calculated ratio is compared with a known threshold for each block. Upon comparison, the IR security mark is detected as a tampered security mark.