Spectral Encoding for Digital Watermarking
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Solution Overview
Problem
Current digital watermarking technologies face challenges in effectively embedding and detecting imperceptible signals in printed objects, particularly in environments with predominantly light-colored or dark-colored designs, where signal visibility and robustness are compromised.
Innovation Solution
The use of specific ink mixtures, such as Phthalocyanine green, Green 7, and Pantone Rubine Red, with high spectral reflectivity differences at 660 nm, combined with advanced image processing methods to encode and decode digital payloads, ensuring robust and imperceptible signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital watermarking is applied to light-colored or dark-colored designs, then signal embedding is achieved, but signal visibility and robustness are compromised
Solution Approach 1:
The patent changes the spectral parameters of the ink by selecting specific pigments (Phthalocyanine green, Green 7, Pantone Rubine Red) that exhibit high spectral reflectivity differences at 660 nm. This parameter change enables the encoded signal to be detected against both light-colored and dark-colored backgrounds by exploiting the wavelength-specific reflectivity characteristics rather than relying on overall color contrast.
Solution Approach 2:
The patent employs spectral oscillation or variation at the 660 nm wavelength region, creating a detectable signal pattern that stands out against the background regardless of the background's overall color. The encoded signal modulates the spectral reflectivity at this specific wavelength, creating a form of spectral 'vibration' that can be detected by scanners tuned to this wavelength.
2Reliability
If ink mixtures with high spectral reflectivity difference are used, then signal robustness is improved, but color accuracy and human perception may be affected
Solution Approach 1:
The patent applies local quality by using ink mixtures with specific spectral characteristics only in the regions where signal encoding is required, while leaving other areas with different color properties unchanged. The Phthalocyanine green, Green 7, and Pantone Rubine Red inks are strategically placed to create spectral contrast at 660 nm without altering the overall visual appearance of the design in non-encoded areas.
Solution Approach 2:
The patent uses composite ink formulations that combine multiple pigments (Phthalocyanine green, Green 7, Pantone Rubine Red) to achieve the desired spectral reflectivity characteristics. These composite inks are engineered to provide high contrast at 660 nm while maintaining acceptable visual appearance across the visible spectrum, effectively balancing signal robustness with aesthetic requirements.
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 approach enables reliable and imperceptible digital watermarking in various design environments, maintaining signal robustness and visibility while minimizing human perception impact.
Implementation Method 1
the white substrate or white background and the ink mixture comprise a spectral reflectivity difference at or around 660 nm in a difference range of 8%-30%
Data Source
AI summary
This disclosure relates to advanced image signal processing technology including encoded signals and digital watermarking. One implementation is directed to a printed object comprising: a white substrate or background comprising a first area; an ink mixture printed at a first plurality of spatial locations within the first area, the ink mixture printed such that the first area comprises a second plurality of spatial locations without the ink mixture, the ink mixture comprising extender white and Green 7 ink, the ink mixture comprising a volume or weight ratio of 97.5% to 99.75% white extender and 2.5%-0.25% Green 7 ink; in which the first plurality of spatial locations is arranged in a pattern conveying an encoded signal, and in which the white substrate or background and the ink mixture comprise a spectral reflectivity difference at or around 660 nm in a difference range of 8%-30%. Of course, other implementations, methods, packages, systems and apparatus are described in this patent document.