AM FM Halftone Watermark Ink Distribution
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Solution Overview
Problem
Existing anti-counterfeiting technologies for documents require special equipment and materials, making them costly and limiting their widespread use for protecting common publications and security documents, while digital watermarks with hybrid halftone dots face instability due to inconsistent dot gains between amplitude modulation (AM) and frequency modulation (FM) halftone dots, necessitating complex density calibration.
Innovation Solution
A manufacturing method for watermarks that disperses ink concentration by filling blank portions within AM halftone dot sets, balancing dot gains with FM halftone dots, allowing for balanced density calibration and improved stability without the need for special equipment or materials, achieved through equidistant spacing and digital halftoning techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If AM halftone dots and FM halftone dots are mixed to form a watermark, then the watermark can provide anti-counterfeiting capability without special equipment, but the dot gains are inconsistent causing unstable distribution density
Solution Approach 1:
The patent changes the parameter of dot spacing by introducing equidistant spacing constraints within AM halftone dot sets. This parameter modification ensures consistent dot gain across different halftone dot types, resolving the instability issue while maintaining the anti-counterfeiting capability of the watermark.
Solution Approach 2:
The patent applies local quality by imposing specific equidistant spacing requirements only within AM halftone dot sets where adjacent ink portions exist, while leaving other regions unchanged. This targeted approach balances the dot gains locally without affecting the overall watermark structure.
2Manufacturing precision
If density calibration is performed to adjust dot distribution density, then the hidden quality of the watermark is ensured, but the process becomes complex requiring careful adjustment
Solution Approach 1:
The patent performs preliminary action by pre-establishing equidistant spacing relationships within AM halftone dot sets before the watermark is generated. This preliminary structuring of dot positions eliminates the need for complex post-generation density calibration, simplifying the process while ensuring consistent hidden quality.
3Shape
If ink concentration is concentrated in AM halftone dot sets, then the watermark pattern is formed, but the dot gain becomes inconsistent with FM halftone dots
Solution Approach 1:
The patent modifies the spacing parameter within AM halftone dot sets by enforcing equidistant positioning of ink portions. This parameter change redistributes the ink concentration uniformly, ensuring that the dot gain matches that of FM halftone dots while preserving the watermark pattern integrity.
Data Source
AI summary
A watermark and a manufacturing method therefor are provided. The watermark has a first region comprising amplitude modulation (AM) halftone dots and a second region comprising frequency modulation (FM) halftone dots, and each of the amplitude modulation halftone dots has ink portions and blank portions, each of which is located between the two ink portions in the same amplitude modulation halftone dot. The ink area percentage of the amplitude modulation halftone dots are dispersed by filling the blank portions into each of the amplitude modulation halftone dots, so that the density calibration of the amplitude modulation halftone dots and frequency modulation halftone dots can be omitted.