Document Authentication via Dynamic Angular Observation
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Solution Overview
Problem
Existing methods for authenticating paper-type documents, such as passports and identity cards, require precise positioning of the document relative to the image sensor and known illumination angles, which limits their applicability in automated and portable authentication systems.
Innovation Solution
A method and system that calculates the position of the image sensor relative to the document and determines the expected aspects of security patterns based on angular observation parameters, allowing for authentication without precise positioning or known illumination angles, using a mobile telecommunications terminal with an image sensor, illumination device, and processing unit that compares detected patterns with stored characteristics to verify authenticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precise positioning of the document relative to the image sensor is required, then authentication reliability is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent changes the parameter of angular observation from a fixed predetermined value to a dynamically determined value based on actual image capture geometry. By calculating the image sensor position relative to the document and deriving angular observation parameters from these calculated positions, the system adapts to varying capture conditions while maintaining authentication reliability.
2Measurement precision
If predetermined positioning of the document is required, then measurement precision is improved, but adaptability deteriorates
Solution Approach 1:
The patent transforms the static predetermined angular parameters into dynamic parameters that are calculated in real-time based on the actual relative position between the image sensor and the document. This allows the system to adapt to different capture positions and orientations while maintaining precise angular measurement for authentication.
Solution Approach 2:
The system automatically determines its own positional parameters by calculating the image sensor position relative to the document and deriving angular observation parameters from these calculations. This self-determination eliminates the need for external positioning equipment or predetermined positioning fixtures.
3Ease of operation
If automated authentication is implemented without precise positioning, then ease of operation is improved, but measurement precision deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the system captures the document image, calculates the actual relative position between the image sensor and document, determines the angular observation parameters based on this calculated position, and then uses these determined parameters to select and compare appropriate reference characteristics. This closed-loop approach maintains measurement precision while enabling automated operation without precise physical positioning.
Data Source
Figure 1~2
AI summary
A method for authenticating at least one document having a predetermined format and bearing at least one security feature whose appearance varies depending on an angle of observation, comprising the steps of: capturing at least one image of the document; determining a shooting angle by comparing geometric features detected in the image of the document and predetermined geometric features stored; deducing an expected appearance of the security feature; comparing the expected appearance with an appearance detected on the image of the document; declaring the document authentic when the expected appearance corresponds to the detected appearance.