Identity Document Imaging for Backlit Hidden Pattern Verification
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Solution Overview
Problem
Existing identity documents with secondary portraits face issues where primary data overlaps with secondary portrait areas, obscuring hidden information and reducing the steganographic capacity, thus compromising authenticity verification.
Innovation Solution
A manufacturing process that calculates a merged digital image combining secondary patterns with a subset of primary data, adding concealed information, and applying it using adjustable laser radiation to ensure visibility under different lighting conditions, allowing for a large secondary motif with integrated hidden information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If primary data is applied to the first surface area of the identity document, then the primary data becomes visible under ambient light conditions, but the hidden information in the overlapping second surface area is masked and cannot be properly verified
Solution Approach 1:
The patent divides the data application areas into distinct first and second surface areas, with the first surface area dedicated to primary data and the second surface area dedicated to secondary portrait with hidden information. This spatial segmentation prevents overlap and masking, allowing both primary data visibility and hidden information verification to function independently without interference.
2Reliability
If the secondary portrait area is limited to portions outside the overlap area with primary data, then hidden information can be verified, but the steganographic capacity is drastically reduced
Solution Approach 1:
The patent utilizes the third dimension (depth/layers) by applying primary data to the first surface area and secondary portrait with hidden information to the second surface area. This dimensional separation allows the secondary portrait to occupy the entire document surface area without being masked by primary data, maximizing steganographic capacity while maintaining verification capability.
3Device complexity
If a single laser is used for applying both primary data and secondary pattern, then the device complexity is reduced, but the manufacturing precision may be compromised due to different visibility requirements
Solution Approach 1:
The patent employs parameter changes by adjusting laser power levels to differentiate between applying primary data and secondary pattern. By varying the laser power parameter, a single laser can achieve the required manufacturing precision for both visible primary data and barely visible secondary pattern with hidden information, eliminating the need for multiple lasers while maintaining quality.
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
Ensures robust authentication by maintaining readability of primary data and concealed information, enhancing security against forgery without reducing the steganographic area, using a single laser for efficient application.
Implementation Method 1
The light radiation performs an ablation of the opaque white photosensitive coating in said second surface area of the identity document
Implementation Method 2
ablation of the opaque white photosensitive coating
Implementation Method 3
using a suitable laser to blacken irradiated dots in one of the outer transparent layers of the identity document
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~4C
AI summary
A method for manufacturing an identity document (10) includes acquiring a set of primary data applicable by light radiation to a first surface area (Z1) of the identity document (10) so as to be visible in ambient light; determining a secondary pattern applicable by light radiation to a second surface area (Z2) so as to be barely visible in ambient light, but visible when backlit by more intense light; calculating a fused digital image comprising the secondary pattern and a subset of primary data intended to be applied to a portion of the first surface area (Z1) overlapping the second surface area (Z2); adding information to be concealed in the fused digital image; and applying by light radiation, to the first and second surface areas (Z1,Z2) of the set of primary data, the secondary pattern and the concealed information.