Authentication Apparatus Frequency Domain Phase Extraction
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Solution Overview
Problem
Existing authentication devices using phase modulation coded security patterns, such as moiré patterns, are difficult to use in consumer and retail applications due to their high precision requirements and the need for prior knowledge of encoding parameters, leading to unsatisfactory decoding quality with residual encoding lines.
Innovation Solution
An authentication method and apparatus that extracts phase modulation information from frequency domain data without requiring prior knowledge of the characteristic frequency, using inverse Fast Fourier Transform and reference axes shifting to digitally filter out the background pattern, allowing for accurate verification of security devices by processing the extracted phase and magnitude information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase modulation coded security patterns such as moiré patterns are used for authentication, then authentication reliability is improved, but the device complexity and precision requirements increase making it difficult to use in consumer applications
Solution Approach 1:
The patent replaces complex mechanical/optical decoding systems with a digital signal processing approach. Instead of requiring precise mechanical alignment and optical equipment to decode moiré patterns, the invention uses digital image processing algorithms to automatically extract authentication information from the frequency domain characteristics of captured images, thereby reducing device complexity while maintaining authentication reliability
Solution Approach 2:
The patent transforms the authentication verification process from spatial domain analysis to frequency domain analysis. By converting the captured moiré pattern image into the frequency domain using Fourier transform, the system can extract characteristic frequency parameters that uniquely identify genuine authentication devices, simplifying the verification process while improving reliability
2Measurement precision
If prior knowledge of encoding parameters is required for decoding, then decoding accuracy is improved, but the ease of operation deteriorates due to the need for manual parameter input
Solution Approach 1:
The patent implements a self-service decoding mechanism where the authentication system automatically determines the encoding parameters from the captured image itself. The system extracts the characteristic frequency and orientation by analyzing the frequency domain representation of the moiré pattern, eliminating the need for manual parameter input while maintaining high decoding accuracy through automatic parameter adaptation
Solution Approach 2:
The patent performs preliminary frequency domain analysis on the captured image to automatically identify and store the encoding parameters before the actual authentication decoding process. This preliminary action of parameter extraction and storage enables subsequent rapid and accurate decoding without requiring users to manually input parameters, thus improving both ease of operation and maintaining decoding precision
3Device complexity
If sampling approach with rectangular image content samples is used, then the decoding process is simplified, but the quality of decoded image deteriorates due to residual encoding lines
Solution Approach 1:
The patent replaces the conventional spatial domain sampling and filtering approach with a frequency domain processing method. By transforming the image to the frequency domain, identifying and removing the characteristic encoding frequency components, then transforming back to spatial domain, the system effectively eliminates residual encoding lines while maintaining simple decoding process architecture
Solution Approach 2:
The patent changes the processing domain from spatial to frequency domain to fundamentally alter how encoding lines are handled. In the frequency domain, the encoding lines appear as distinct frequency components that can be selectively removed through frequency filtering, thereby improving decoded image quality without significantly increasing process complexity
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 method enables accurate and efficient verification of authentication devices, eliminating the need for prior knowledge of encoding parameters and reducing residual encoding lines, making it suitable for consumer and retail applications by providing a more reliable and user-friendly authentication process.
Implementation Method 1
The processor is to transform pixel data into frequency domain data
Implementation Method 2
shifting of the reference frequency axes in the frequency domain such that a new origin is at a dominant frequency
Implementation Method 3
relative frequency domain data are transformed into spatial domain data after the characteristic frequency offset. Phase and/or magnitude information may then be extracted from said spatial domain data
Data Source
AI summary
A method of and an apparatus for verifying authenticity of a target authentication device comprising a reference pattern having a characteristic frequency and a security pattern, the security pattern comprises an embedded security device that is coded with phase modulation information. The method comprises extracting frequency domain data from an image of the target authentication device to facilitate verification of authenticity of the target authentication device. The method provides a very effective end expedient mechanism for verifying authenticity of a moiré or moiré like authentication device to combat counterfeiting.