Document Image Security via Composite Ground Pattern Segmentation
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Solution Overview
Problem
Existing image processing technologies fail to effectively prevent the removal of ground patterns used for replication prevention in document images, especially when scanned and converted into electronic data, leading to insufficient security and readability issues.
Innovation Solution
An image processing apparatus and program that includes a ground pattern detector, latent image extractor, lightness corrector, and color converters to maintain the ground pattern's security and readability by detecting and processing the ground pattern within the image, correcting lightness, and converting colors to prevent removal during image processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ground pattern is superposed on a document image to prevent replication, then security against copying is improved, but the ground pattern can be easily removed when the image is scanned and processed electronically
Solution Approach 1:
The patent applies composite materials by combining multiple patterns with different resolutions (high screen ruling pattern and low screen ruling pattern) to form a ground pattern that functions as a unified security feature. This composite structure ensures that the ground pattern maintains its integrity against various copying and scanning operations, as the different resolution patterns interact in ways that prevent easy removal or detection of the security feature.
2Reliability
If the ground pattern is designed with high resolution to prevent removal, then security is improved, but readability of the document image deteriorates
Solution Approach 1:
The patent segments the ground pattern into multiple distinct patterns with different resolutions. The high screen ruling pattern provides fine detail that is difficult to replicate, while the low screen ruling pattern ensures broader visibility and readability. This segmentation allows each component to serve its specific function while collectively maintaining both security and document readability.
Solution Approach 2:
Different regions of the ground pattern have different resolution properties tailored to their specific functions. The high screen ruling portions provide security-critical features that are difficult to copy, while adjacent low screen ruling portions maintain document readability. This local differentiation of quality ensures that security requirements are met without compromising overall document usability.
3Adaptability or versatility
If electronic data is processed to change lightness or color, then distribution flexibility is improved, but the ground pattern can be easily removed or altered
Solution Approach 1:
The ground pattern is embedded in the document image at the earliest stage of electronic data creation, before any processing or distribution operations. This preliminary embedding ensures that the security feature is integrated into the fundamental structure of the electronic data, making it resistant to subsequent processing operations such as lightness or color adjustments that might otherwise remove or alter the pattern.
Data Source
AI summary
An image input from an image input unit is divided into a ground portion and a document other than the ground portion in an image divider, and a latent image is extracted from a ground pattern included in the ground portion in a latent image extractor. Lightness of the latent image is corrected to be closer to lightness of the document in a lightness corrector, and a color of the latent image is converted into a gradation A in a latent image converter. A color of the document is converted in a document converter into a gradation B including the same plurality of colors as gradation A and having a different manner of gradation. The latent image and the document are integrated in an image integrator to generate an image including the latent image and the document having similar lightness with a difference in hues superposed on each other.