Printer Color Lookup Table Optimization for Constancy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current color reproduction technologies face challenges in maintaining color constancy and smoothness, especially when prints are viewed under different lighting conditions, due to the introduction of redundancy with the addition of black ink in CMYK printers, which can negatively affect color accuracy.
Innovation Solution
A method and system for creating a color lookup table that uses a non-linear minimization algorithm to determine device-specific colorant combinations based on a printer model, incorporating an image quality metric that includes a color inconstancy index and gray component replacement strategy to optimize colorant combinations for improved color constancy and smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If black ink is added to CMY printer to create CMYK system, then printing cost is reduced and gray component replacement is enabled, but color constancy is negatively affected
Solution Approach 1:
The patent changes the parameters of colorant combination selection by using an image quality metric that incorporates color inconstancy index. Instead of using traditional GCR methods that simply replace gray components with black ink, the system optimizes the combination of CMYK colorants by minimizing color variation under different illuminants, thus maintaining color constancy while enabling cost-effective black ink usage.
Solution Approach 2:
The patent introduces feedback mechanisms by evaluating color inconstancy index and image quality metrics during the colorant combination selection process. The system continuously adjusts the colorant combinations based on how well they maintain color appearance under varying lighting conditions, creating a closed-loop optimization that balances cost and color accuracy.
2Ease of manufacture
If gray component replacement strategy is used to control black ink amount, then printing cost is reduced, but color constancy is negatively affected
Solution Approach 1:
The patent applies composite material principles by combining multiple colorants (C, M, Y, K) in optimized proportions rather than relying on simple GCR replacement. The system creates composite colorant combinations that leverage the strengths of each ink type, using black ink strategically while maintaining color accuracy through the synergistic interaction of all four colorants.
Solution Approach 2:
The system dynamically changes the parameters of colorant combinations based on the specific color region and lighting conditions. Instead of applying a fixed GCR strategy, the patent optimizes the amount and distribution of black ink and other colorants for each specific color point, thereby maintaining color constancy while controlling printing costs.
3Adaptability or versatility
If multiple CMYK colorant combinations can produce the same color, then flexibility is increased, but color accuracy and smoothness become difficult to maintain
Solution Approach 1:
The patent introduces dynamics by making the colorant combination selection adaptive rather than static. The system dynamically selects the optimal CMYK combination for each color point based on multiple criteria including color accuracy, smoothness, and color inconstancy index. This dynamic selection process ensures that among the multiple possible combinations, the one that best maintains color accuracy and smoothness is chosen.
Solution Approach 2:
The patent replaces traditional mechanical/empirical color separation methods with an algorithmic optimization system. Instead of relying on fixed rules or manual adjustment of colorant combinations, the system uses computational optimization with image quality metrics to automatically select the best combinations, thereby maintaining precision despite the flexibility of multiple possible solutions.
Data Source
AI summary
Color separation systems and methods improve color constancy and smoothness of a color lookup table (LUT) for a printer. A plurality of nodes of the LUT may be defined in colorimetric space, and the nodes out of the printer gamut may be mapped to the printer gamut surface. A set of possible colorant combinations are then determined that produce each node in the LUT in a device independent color space using a non-linear minimization algorithm, such as, for example, a conjugate gradient algorithm. Next, a colorant combination may be determined for each and every node in the LUT based on an image quality metric. In some implementations, a smoothing filter may be used to smooth the lookup table.