Scrambled Pixel Arrangement for Identity Document Security
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Solution Overview
Problem
Conventional security devices for authenticating identity documents, such as identity cards and passports, are vulnerable to tampering due to their periodic pixel arrangements, which can be easily replicated by unauthorized individuals, leading to visual artefacts and security breaches.
Innovation Solution
The implementation of a scrambled spatial and colorimetric arrangement of pixels, where each pixel comprises multiple sub-pixels with unique color assignments and variable shapes and positions, encoded in a coding system that only authorized operators can decipher for correct image production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a periodic pixel arrangement is used for personalization, then the manufacturing process is simple and easy to implement, but the security is compromised and unauthorized replication becomes possible
Solution Approach 1:
The patent applies asymmetry by replacing the symmetric periodic pixel arrangement with an asymmetric scrambled arrangement. Each pixel's sub-pixels are positioned at asymmetric coordinates determined by a scrambling function, making the overall pattern non-repetitive and unpredictable. This asymmetric structure prevents unauthorized replication while maintaining manufacturability through algorithmic generation of the arrangement.
Solution Approach 2:
The patent changes the parameters of the pixel arrangement by introducing scrambling variables (a, b, c, d) that transform the standard periodic coordinates into scrambled coordinates. This parameter transformation allows the same manufacturing process to produce secure patterns by simply changing the mathematical parameters rather than the physical manufacturing method.
2Reliability
If a scrambled pixel arrangement is implemented to enhance security, then unauthorized replication becomes difficult, but the manufacturing complexity increases
Solution Approach 1:
The patent replaces the physical/mechanical aspect of creating unique patterns with a mathematical/computational system. Instead of using complex physical manufacturing processes to create unique pixel arrangements, the invention uses a scrambling function based on modular arithmetic to generate the arrangement. This substitution of mathematical operations for mechanical complexity achieves security without proportionally increasing manufacturing difficulty.
Solution Approach 2:
The scrambling function serves multiple purposes: it creates the asymmetric pixel arrangement for security, it can be parameterized to generate different patterns for different documents, and it maintains compatibility with existing manufacturing processes. This multi-functionality reduces the need for separate complex systems for each security requirement.
3Ease of operation
If sub-pixels are arranged in a regular periodic pattern, then the image production is straightforward, but visual artefacts such as Moiré fringes appear
Solution Approach 1:
By scrambling the periodic arrangement into an asymmetric pattern, the invention eliminates the regular intervals that cause Moiré fringes and other visual artefacts. The asymmetric distribution of sub-pixels breaks the constructive interference patterns that create harmful visual effects, while the underlying mathematical structure maintains ease of image production through algorithmic control.
4Reliability
If the pixel arrangement is made asymmetric and scrambled, then security is enhanced, but the programming complexity for image production increases
Solution Approach 1:
The patent replaces complex procedural programming with a mathematical formula-based approach. The scrambling function using modular arithmetic provides a deterministic yet complex pattern generation method that enhances security while keeping programming relatively simple. The formulaic approach is more efficient than complex procedural code for generating the asymmetric arrangements.
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 significantly enhances the security of identity documents by making unauthorized reproduction of images difficult, as the scrambled arrangement acts as an encryption, making tampering detectable and preventing false image creation.
Implementation Method 1
The principle of laser engraving consists in thermally modifying the image layer to modify its color, which then typically changes from white or transparent to black by carbonization.
Data Source
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AI summary
A pixel arrangement designed to be customized to create an image, the pixels (3) forming a tiling of an image surface (2), each pixel (3) comprising a plurality of N contiguous sub-pixels (4), each containing a different color chosen from N complementary colors, the arrangement being spatially and/or colorimetrically scrambled relative to a spatially and colorimetrically periodic arrangement. A security device comprising such an arrangement (1). An identity document comprising such an arrangement (1). A coding of such an arrangement (1). A method for personalizing such an arrangement (1).