Color Artwork Signal Embedding With Luminance-Constrained CMY
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Solution Overview
Problem
Existing technologies face challenges in efficiently encoding information signals in color artwork and printed objects while maintaining low luminance change and preserving robustness, particularly in applications with limited image variability.
Innovation Solution
The method involves altering cyan, magenta, and yellow values in color images to embed information signals, minimizing luminance changes and ensuring robustness by adjusting ink values to maintain target reflectance values, using techniques such as changing cyan and magenta values in opposite directions to reduce luminance differences and employing error correction coding and synchronization signals for reliable decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If information signals are encoded in color artwork by altering ink values, then data encoding capability is improved, but luminance change increases which reduces visual quality
Solution Approach 1:
The patent changes the color parameters (Cyan, Magenta, Yellow, Black ink values) of the artwork pixels to embed information signals. By specifically adjusting the Magenta channel in response to Cyan changes, the system modifies color parameters while controlling luminance parameters to remain within acceptable thresholds, thus encoding information without excessive visual degradation
Solution Approach 2:
The patent applies different adjustment strategies to different color channels locally. Specifically, when Cyan values are changed to encode signal bits, Magenta values are adjusted in the opposite direction at the same pixel locations to compensate for luminance changes. This localized compensation approach ensures that information encoding occurs while maintaining visual quality at each specific location
2Loss of information
If ink values are altered to embed signals, then data hiding capability is improved, but color accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the adjustment of Magenta values is determined by the magnitude and direction of Cyan value changes. The system calculates the luminance change caused by signal embedding and uses this feedback to adjust Magenta in the opposite direction, thereby compensating for color shifts and maintaining color accuracy while preserving signal embedding capability
Solution Approach 2:
The patent uses Magenta channel adjustments as a counterweight to offset the luminance changes caused by Cyan channel modifications. By changing Magenta in the opposite direction to Cyan changes, the system creates a compensating effect that counterbalances the color accuracy deterioration, allowing signal embedding while preserving overall color fidelity
3Reliability
If robustness is increased by modifying more pixels, then signal detection reliability is improved, but luminance change increases reducing imperceptibility
Solution Approach 1:
The patent applies partial action by selectively adjusting only the Magenta channel in response to Cyan modifications, rather than increasing the overall number of modified pixels. This targeted approach provides sufficient robustness for signal detection by ensuring that the compensated pixels maintain both signal integrity and visual imperceptibility, avoiding the need to modify excessive pixels which would increase luminance changes
Data Source
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AI summary
The present disclosure relates generally to signal encoding for printed objects such as product packaging, labels and hangtags. One implementation obtains a color image representing CMY color channels, and alters the color image to include an encoded signal by altering values representing CIELAB a* and b*, all the while keeping L* on or within a predetermined tolerance of a contour representing a constant value. Other implementations are provided.