Invisible Mark Detection on Cards via Chrominance Analysis

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Solution Overview

Problem

Current methods for detecting fraudulent cards using invisible marks are time-consuming and require expensive special devices that need to illuminate the card over multiple wavelengths, making them inefficient for rapid determination in criminal investigations.

Innovation Solution

A method that normalizes and calculates chrominance light differences from a card image using a mobile phone camera, allowing for the detection of invisible marks in the visible ray region by stretching histograms to identify refractive index changes, thereby reducing the need for multiple wavelength illumination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If special devices with multiple wavelength light sources are used to detect invisible marks, then detection reliability is improved, but device complexity and examination time increase

Engineering Contradiction:

Improvedetection reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the necessary chrominance information from the captured image by calculating differences between normalized light channels (R-G, G-B, etc.), eliminating the need for complex multi-wavelength illumination systems while maintaining detection reliability through selective feature extraction

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a digital copy of the card image and performs chrominance calculations on the copied data, allowing repeated analysis of the same image without requiring repeated physical illumination, thus simplifying the detection system while maintaining reliability

Inventive Principle:

Principle #26Copying

2Measurement precision

If multiple wavelength illumination is repeatedly applied to detect invisible marks, then detection precision is improved, but examination time increases

Engineering Contradiction:

Improvedetection precisionVSAvoidexamination time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary normalization of the captured image data and pre-calculates chrominance differences between light channels, enabling rapid detection without requiring repeated illumination sequences, thus reducing examination time while maintaining precision through preliminary data processing

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent continuously processes the captured image data through normalization and chrominance calculation in a single continuous operation, eliminating the intermittent repeated illumination steps required by traditional methods, thereby reducing total examination time while maintaining detection precision

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If expensive special devices with bandpass filters are used, then detection reliability is improved, but cost increases

Engineering Contradiction:

Improvedetection reliabilityVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive special devices with a standard camera and simple image processing algorithms, using disposable computational methods instead of costly hardware, thereby reducing cost while maintaining detection reliability through software-based chrominance analysis

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the mechanical optical systems (bandpass filters, specialized illuminators) with digital image processing operations (normalization, chrominance calculation), eliminating the need for expensive optical components while maintaining detection reliability through computational analysis

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 rapid determination of fraudulent cards by detecting invisible marks in the visible ray region, reducing investigation time and eliminating the need for expensive special devices, allowing for immediate identification using a mobile phone.

Implementation Method 1

detecting an invisible mark indicated in a card in a visible ray region using a characteristic in which a color tone of light is changed due to a difference in the refractive index of a wavelength according to a medium in the visible ray region

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9536162B2Method for detecting an invisible mark on a card

Publication Date: 2017.01.03 REPUBLIC OF KOREA (NTL FORENSIC SERVICE DIRECTOR MINIST OF PUBLIC ADMINISTRATION & SECURITY)

AI summary

The present invention relates to a method for detecting a mark that is invisible in the visible light region. Here, the invisible mark is displayed on a card using a characteristic according to which the color of light is changed by means of a refractive index difference according to media in the visible light region. According to the method for detecting the invisible mark, it may be quickly determined whether the card is a counterfeit card in an investigation. In addition, since it is unnecessary to repeatedly inspect the card to be checked using various wavelengths, the time required for determining whether the card is a counterfeit card may be reduced.