Printer Color Profile Generation Using Error-Corrected Lookup Tables
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Solution Overview
Problem
Current methods for generating accurate color profiles in color printing devices require a large number of patches, which is time-consuming and prone to errors, especially when dealing with flexible substrates, and existing models are not accurate enough for universal application, particularly with fluorescent colors.
Innovation Solution
A method that uses measured ink combination data to compute error correction factors for prediction models, allowing for the reduction of the number of patches needed while maintaining accuracy, by introducing a correction function to predict the actual color based on the difference between measured and predicted values, applicable to various prediction models like Kubelka-Munk theory and multiplicative relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of patches are used to generate accurate color profiles, then color profile accuracy is improved, but time consumption and operational complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing lookup tables (LUTs) that contain correction factors for predicting overprint colors. Instead of performing complex spectral measurements and calculations for every patch during profiling, the system pre-computes these correction factors based on the prediction model and measured ink combinations, allowing rapid application during actual color profile generation without time-consuming real-time calculations.
Solution Approach 2:
The patent replaces the mechanical/manual process of measuring every patch with a computational system. Instead of physically measuring each patch with a spectrophotometer, the system uses a prediction model combined with pre-computed lookup tables to calculate expected colors, then applies error correction factors derived from a subset of measured patches. This substitution of mechanical measurement with computational prediction dramatically reduces time consumption while maintaining accuracy.
2Measurement precision
If a large number of patches are used to generate accurate color profiles, then color profile accuracy is improved, but the number of operations and potential for errors increase
Solution Approach 1:
The patent applies segmentation by dividing the color profiling process into distinct stages: (1) measuring a small set of ink combinations, (2) computing correction factors from these measurements, (3) storing these factors in lookup tables, and (4) applying the lookup tables to predict colors for all patches. This segmentation allows the complex task of profiling many patches to be broken down into manageable steps, reducing operational complexity while maintaining accuracy through the use of correction factors derived from the segmented measurement process.
Solution Approach 2:
The patent introduces lookup tables as an intermediary between the measured ink combinations and the final color profile. These LUTs contain pre-computed correction factors that mediate the relationship between a small set of actual measurements and the large number of patches that need to be profiled. This intermediary structure simplifies the operational process by providing a ready-reference correction mechanism rather than requiring complex real-time calculations for each patch.
3Ease of manufacture
If existing prediction models are used without error correction, then the process is simpler, but accuracy is insufficient particularly with fluorescent colors
Solution Approach 1:
The patent applies feedback by measuring actual ink combinations, comparing the measured values with prediction model outputs, calculating the differences (errors), and using these errors to compute correction factors. These correction factors are then fed back into the prediction process through the lookup tables, continuously improving accuracy. This feedback loop allows the system to learn from measurement errors and compensate for model deficiencies, particularly with challenging ink types like fluorescent colors, while maintaining process simplicity through automated correction.
Data Source
AI summary
The present invention relates to a method of generating “expanded color chart” representing various ink combination, for profiling a multi-color printing device or printer, using “reduced set of color chart”, printed using the printer, wherea. The expanded color chart is computed by applying “Error Correction” function to the expanded color chart predicted using a theoretical model of color prediction for a given ink combinations in the expanded chart.b. Error Correction function is computed/modelled as function of the variance/difference observed between the color values predicted by the theoretical model and the actual values measured for the ink combinations in the printed “reduced set of color chart”.