Regularizing n-ink Color Models to Eliminate Banding Artifacts
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Solution Overview
Problem
Current color management systems face challenges in accurately and continuously reproducing colors on color devices, particularly due to singular or degenerated three-ink models that result in banding artifacts and rainbow effects, and non-regular four-ink models that fail to maintain color accuracy under varying GCR/UCR settings.
Innovation Solution
The method involves creating a regular n-ink model by extending the color and colorant values with gloss characterization, using a printed printer target with extra sampling points, and adapting look-up tables to ensure smooth color gradations and vignettes, and includes techniques to check for measurement errors and adjust the model to limit the colorant domain properly, ensuring a well-behaving separation table.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional n-ink model is used for color reproduction, then the color reproduction process is simple, but banding artifacts and rainbow effects occur due to singular or degenerated models
Solution Approach 1:
The patent applies preliminary action by detecting singular or degenerated three-ink models before color reproduction occurs, and by pre-defining regularized four-ink models with proper GCR/UCR settings. This prevents banding artifacts and rainbow effects from occurring in the first place, rather than correcting them after they appear.
Solution Approach 2:
The patent changes parameters by introducing regularization criteria for n-ink models, modifying the mathematical representation of colorant relationships. It transforms singular or degenerated models into regular models by adjusting the underlying parameters of the color reproduction equations, ensuring stable and artifact-free color output.
2Adaptability or versatility
If GCR/UCR settings are varied to improve color accuracy, then color reproduction flexibility increases, but non-regular four-ink models fail to maintain color accuracy
Solution Approach 1:
The patent applies dynamics by creating regularized four-ink models that can dynamically adapt to different GCR/UCR settings while maintaining color accuracy. The model structure allows flexible adjustment of gray component replacement and undercolor removal parameters without sacrificing mathematical regularity or color reproduction fidelity.
Solution Approach 2:
The patent implements feedback mechanisms by incorporating regularization checks that monitor whether four-ink models maintain proper mathematical properties under varying GCR/UCR settings. This feedback ensures that color accuracy is preserved across different operational conditions by preventing the model from entering non-regular states.
3Measurement precision
If measurement points are increased to improve model accuracy, then color reproduction precision improves, but the complexity of the printing process increases
Solution Approach 1:
The patent applies preliminary action by establishing regularization criteria and mathematical frameworks before actual color measurement and reproduction. This pre-established structure allows for efficient processing of measurement data without requiring excessively complex computational procedures during the printing process.
Solution Approach 2:
The patent applies local quality by focusing regularization efforts on specific critical regions of colorant space where singularities and degenerations most commonly occur. This targeted approach improves measurement precision where it matters most without uniformly increasing complexity across the entire color reproduction process.
Data Source
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AI summary
The method comprises the steps of : selecting an n-ink model for the color device, for transferring a set of colorant values in colorant space to a set of color values in color space; selecting a printer characteristic of the n-ink model, wherein the printer characteristic indicates the regularity of the n-ink model; evaluating, for the n-ink model, a set of one or more values and/or ranges for the printer characteristic, thus determining the regularity of the n-ink model; modifying the n-ink model such that the modified n-ink model is regular, if, based on the evaluation, the n-ink model was not regular.