Multi-Modal Security Feature Verification Using Optical and Ultrasonic Data Fusion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for verifying security features, such as watermarks in value documents, face challenges in distinguishing genuine from counterfeit due to limitations in security checks, particularly with the use of either optical or ultrasonic sensors alone.
Innovation Solution
A method that combines spatially resolved optical and ultrasonic data to check security features, where pixel data and ultrasonic data are processed together to form reduced-resolution images, allowing for a comparison signal to indicate the presence or absence of the security feature, enhancing the accuracy of authenticity verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only optical sensors are used to detect security features, then the device complexity is low, but the measurement precision and reliability of distinguishing genuine from counterfeit documents is insufficient
Solution Approach 1:
The patent combines optical sensors and ultrasonic sensors into a single detection system. The optical sensor captures images of the document surface while the ultrasonic sensor detects subsurface thickness variations. By merging these two different sensing modalities, the system achieves higher measurement precision in distinguishing genuine documents from counterfeits, as each sensor type compensates for the limitations of the other.
Solution Approach 2:
The patent transitions from two-dimensional optical image analysis to three-dimensional thickness measurement by introducing ultrasonic sensing. The ultrasonic sensor measures the time-of-flight of sound waves to determine subsurface thickness variations, adding a depth dimension to the detection process. This dimensional enhancement allows for more accurate detection of watermark security features that are not visible on the surface.
2Measurement precision
If only ultrasonic sensors are used to detect security features, then the measurement precision for subsurface features is improved, but the device complexity increases and processing time is extended
Solution Approach 1:
The patent performs optical image capture first to identify the document type and locate security feature areas. This preliminary action allows the system to pre-process and segment the document image, marking regions of interest before ultrasonic scanning. By preparing the optical data in advance, the subsequent ultrasonic measurement can be focused on specific areas, reducing overall processing time while maintaining high precision.
Solution Approach 2:
The patent divides the document detection process into distinct segments: optical image acquisition, image processing and analysis, ultrasonic scanning, and data fusion. Each segment handles specific tasks independently, allowing for optimized processing of each modality. The optical segment identifies document characteristics while the ultrasonic segment focuses on thickness measurement, and their results are fused for final authentication.
3Measurement precision
If high-resolution optical imaging is performed, then the detection detail is improved, but the data processing complexity and time increase when matching with ultrasonic data
Solution Approach 1:
The patent applies partial action by processing only the necessary portions of the high-resolution optical image. Instead of processing the entire image at full resolution, the system identifies and processes only the security feature areas where ultrasonic measurements are taken. This selective processing maintains high detection detail in critical regions while significantly reducing overall data processing complexity and time.
Solution Approach 2:
The patent applies local quality by using different processing resolutions for different regions of the document. High-resolution optical processing is applied only to security feature areas such as watermarks and security threads, while other regions are processed at lower resolution or skipped entirely. This localized high-quality processing maintains detection precision where needed while reducing overall computational burden.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the security of authenticity checks by effectively combining optical and ultrasonic data to verify the presence of security features, reducing the likelihood of misidentification and enhancing the reliability of distinguishing genuine from counterfeit documents.
Implementation Method 1
the sheet material is subjected to sound, in particular ultrasound, and the sound transmitted through the sheet material and/or reflected on the sheet material is measured
Implementation Method 2
the sound transmitted through the sheet material and/or reflected on the sheet material is measured
Implementation Method 3
pixel data are detected which is an optical image of at least security feature area of the document of value
Implementation Method 4
pixel data are detected which is an optical image of at least security feature area of the document of value with a specified optical spatial resolution
Data Source
Figure 1~8
Figure 2~4
Figure 5~7
AI summary
The invention relates to a method for examining a pre-defined security feature of a value document, which is present in an pre-defined security feature area of the value document, in particular a water mark, comprising detecting pixel data that depict, in a spatially resolved manner, an optical image of at least the security feature area of the value document with a pre-defined optical spatial resolution; detecting ultrasound data that depict, in a spatially resolved manner, an ultrasound feature of the value document with a defined ultrasound spatial resolution, at least in the security feature area, wherein the ultrasound spatial resolution is lower than the optical spatial resolution; detecting, from the pixel data, first resolution-reduced pixel data for resolution-reduced pixels of a first resolution-reduced image, which depict a resolution-reduced optical image of at least the security feature area of the value document, the optical spatial resolution of which corresponds to the ultrasound spatial resolution such that first resolution-reduced pixel data are assigned to the respective spaces dedicated to the ultrasound data; and at least examining to what extent the first resolution-reduced pixel data correspond with the ultrasound data.