Halftone Screen Signatures for Print Source Validation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing halftone screens in printing technologies fail to effectively embed a discernible pattern that can validate the source of a printed output, leading to potential security issues and image quality degradation due to moiré patterns.
Innovation Solution
Designing halftone screens to intentionally include a unique signature pattern that can be visually or optically detected, ensuring each request generates a distinct pattern, which is embedded in the printed output to validate its origin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional halftone screens are used for printing, then printing functionality is achieved, but security validation capability is lacking and moiré patterns appear
Solution Approach 1:
The halftone screen is segmented into multiple frequency components, each serving a different function: a first frequency component encodes security signature information while a second frequency component maintains normal printing functionality. This segmentation allows the screen to simultaneously provide security validation and avoid moiré patterns by separating their respective frequency ranges.
Solution Approach 2:
Different regions of the halftone screen are assigned different properties: certain areas contain high-frequency signature patterns for security validation, while other areas use traditional lower-frequency patterns for normal printing. This local differentiation enables the screen to perform multiple functions without compromising overall image quality or generating harmful moiré artifacts.
2Reliability
If halftone screens embed signature patterns for security validation, then security is improved, but image quality may degrade due to visible patterns
Solution Approach 1:
The signature pattern is embedded in the frequency domain rather than the spatial domain. By encoding security information at a different frequency dimension that is imperceptible to human vision, the patent achieves security validation without degrading visible image quality. The signature becomes detectable only through optical analysis at specific frequencies.
Solution Approach 2:
The patent uses frequency modulation analogous to color space transformation, where the signature pattern exists in a frequency 'color' space that is invisible to human perception but detectable by optical sensors. This allows the signature to be embedded without affecting the visible 'color' or appearance of the printed image.
3Measurement precision
If a unique signature pattern is generated for each request, then security validation accuracy is improved, but system complexity increases
Solution Approach 1:
The patent generates unique signature patterns by varying specific parameters such as frequency, amplitude, or phase of the halftone screen components based on request identifiers. This parameter-based generation method enables high precision in signature detection while maintaining relatively simple generation logic, as the same base algorithm is used with different input parameters for each unique signature.
Data Source
AI summary
In an example, a method includes, at least one processor, in response to each of a plurality of requests, determining a halftone screen. Determining the halftone screen comprises encoding a signature pattern in the halftone screen, and halftone screens for different requests may be encoded with a different signature pattern. The halftone screen may be arranged such that, when applied to image data to provide a printed output, the pattern is discernible therein to provide a signature for the printed output.