Security Feature With Frequency-Embedded Codes
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Solution Overview
Problem
Existing security features can be easily duplicated by photocopying and require complex image processing for authentication, making them susceptible to errors and unauthorized reproduction.
Innovation Solution
A method involving embedding machine-readable codes in a two-dimensional discrete complex function, which is Fourier transformed and binarized, resulting in a high-resolution image that is difficult to copy and requires specific conditions for reconstruction, using a linked image with a high pixel resolution and unique printing colors to prevent unauthorized reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional security features with encoded images are used, then information can be stored and displayed, but the security element can be easily duplicated by photocopying
Solution Approach 1:
The patent embeds machine-readable codes within the frequency spectrum of a Fourier-transformed image rather than directly in the spatial domain. By placing codes in the frequency domain (specifically in high-frequency regions), the security feature becomes invisible in the original image space while remaining recoverable through spectral analysis, thus preventing photocopying duplication.
Solution Approach 2:
The patent introduces Fourier transformation as an intermediary process to hide the machine-readable codes within the frequency spectrum of an image. The codes are not directly visible in the original image but can be extracted through spectral analysis, creating a layered security mechanism that prevents simple photocopying while maintaining visual aesthetics.
2Reliability
If machine-readable codes are directly embedded in security features, then authentication can be performed, but the codes can be easily reproduced by photographing or photocopying
Solution Approach 1:
The patent transitions the machine-readable codes from the spatial domain to the frequency domain through Fourier transformation. The codes are embedded in the frequency spectrum where they are invisible in the original image but can be extracted through spectral analysis, preventing simple reproduction by photographing or photocopying.
Solution Approach 2:
The patent changes the domain parameters of the code embedding from spatial coordinates to frequency coordinates. By representing codes in the frequency domain with specific spectral characteristics, the system enables authentication while preventing simple reproduction, as the codes require spectral transformation for extraction.
3Reliability
If high-resolution linked images are printed with specific pixel resolutions, then photocopying is prevented, but authentication requires precise frequency coordinate analysis
Solution Approach 1:
The patent embeds authentication data in the frequency domain rather than the spatial domain. The high-resolution printing prevents photocopying by preserving fine spatial details, while the frequency-domain embedding requires spectral analysis for authentication, creating a two-layer security mechanism.
Solution Approach 2:
The patent replaces simple visual inspection or basic image processing with Fourier spectral analysis for authentication. The system substitutes mechanical/visual verification with a mathematical transformation approach, where authentication requires analyzing the frequency spectrum rather than just comparing visual patterns.
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
The method creates a security feature that is resistant to photocopying and allows for efficient machine-readable authentication, ensuring the security feature's integrity and preventing unauthorized reproduction.
Implementation Method 1
The two-dimensional discrete complex function G (fx, fy) is Fourier transformed and binarized, resulting in a high-resolution image
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The invention relates to a method for producing a security feature (4) by providing a first item of information as an open, machine-readable, first graphical code (1), providing the first graphical code (1) as a first image, providing at least one further item of information in at least one machine-readable further graphical code (2, 3), embedding the at least one further graphical code (2, 3) in a two-dimensional, discrete, complex function G(fx,fy) having an fx frequency coordinate and an fy frequency coordinate, subjecting the two-dimensional, discrete, complex function G(fx,fy) to a Fourier transform to form a two-dimensional, discrete, complex function g(x,y), and binarizing the function g(x,y) to form a second image, and linking the first and second images to one another, wherein a maximum used frequency fx_max, fy_max and a maximum achievable frequency fx_limit, fy_limit are each determined along both frequency coordinates fx, fy, a ratio Pfx = (I), Pfy = (II) of the maximum used frequency and the maximum achievable frequency is determined along each coordinate, and the linked image is printed with a pixel resolution of at least the smaller value of the two values (III), (IV).