Watermark Authentication via Reflected Light Correlation
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Solution Overview
Problem
Existing methods for authenticating paper sheets, such as bills, using watermarks are vulnerable to counterfeiting as they rely on light-based identification, which can be replicated by printing similar images on counterfeit surfaces, leading to challenges in accurately distinguishing authentic from counterfeit bills.
Innovation Solution
A paper sheet identification apparatus that utilizes light receiving means to capture reflected light from watermarked images, converts it into pixel data containing color information, and calculates a correlation coefficient with transmitted light data from a legitimate watermark to determine authenticity, employing multiple light sources and a converter to enhance identification accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light-based identification is used to authenticate watermarks on paper sheets, then the authentication process is simple and cost-effective, but the system becomes vulnerable to counterfeiting as counterfeit images can be printed to replicate the watermark appearance
Solution Approach 1:
The patent changes the detection parameter from simple light presence to correlation coefficient calculation. By comparing the correlation between reflected light pattern and transmitted light pattern, the system detects subtle differences that counterfeit images cannot replicate, even when they visually resemble the original watermark.
Solution Approach 2:
The patent introduces correlation coefficient as an intermediary metric between the light patterns and authenticity determination. This intermediary allows the system to objectively quantify the relationship between reflected and transmitted light patterns, providing a reliable basis for authentication that goes beyond simple visual similarity.
2Measurement precision
If multiple light sources and correlation coefficient calculation are used to improve authentication accuracy, then identification precision increases, but device complexity increases
Solution Approach 1:
The patent segments the authentication process into distinct functional modules: light receiving means for capturing reflected light, converter for transforming light signals to pixel data, and identification processing for calculating correlation coefficients. This segmentation allows each component to perform its specific function efficiently, managing complexity through modular design.
Solution Approach 2:
The patent makes the light receiving means perform multiple functions: it captures reflected light patterns, converts them to pixel data, and provides input for correlation coefficient calculation. This multi-functionality reduces the need for separate dedicated components for each processing stage, thereby managing device complexity while maintaining high measurement precision.
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 effectively identifies the authenticity of paper sheets by leveraging the contrast inversion between transmitted and reflected light, improving accuracy and preventing counterfeiting without increasing costs, and can be applied to various paper-based documents like bills, gift certificates, and coupons.
Implementation Method 1
light receiving means for receiving reflected light from a watermarked image formed on a paper sheet to be conveyed
Implementation Method 2
a converter which converts the reflected light from the watermarked image being received by the light receiving means into data for each pixel of a predetermined size as a unit, which contain color information having brightness
Data Source
AI summary
A paper sheet identification apparatus capable of identifying an authenticity of a watermark area formed on a paper sheet is provided without increasing the cost. The paper sheet identification apparatus includes: a light receiving part receiving reflected light from a watermarked image formed on a paper sheet to be conveyed, a converter converting the reflected light from the watermarked image received by the light receiving part for each pixel as a unit of a predetermined size including color information having brightness; and an identification processing part identifying the authenticity of the watermarked image based on a correlation coefficient, which is calculated from a density value for each pixel converted by the converter and a density value for each pixel by the transmitted light from the watermarked image of the bill serving as a reference.