Color Chart Spectral Reflectance Correction for Halftone Dot Mapping

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Solution Overview

Problem

Existing methods for predicting and correcting color chart data for overprinted inks, such as the Deshpande et al. method, require printing multiple CxF charts, leading to increased costs and man-hours, and the predicted spectral reflectances often need manual adjustment, which is difficult and error-prone.

Innovation Solution

A method and program for correcting color chart data by associating dot percents with spectral characteristics, allowing intuitive adjustment of dot percents and spectral characteristics using computer-assisted processes, including SCTVs conversion and reference candidate color selection, to facilitate easy correction of spectral reflectances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple CxF charts are printed for color measurement, then color prediction accuracy is improved, but manufacturing cost and time consumption increase

Engineering Contradiction:

Improvecolor prediction accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent uses measured spectral reflectance data from physical CxF charts to create a digital color chart data structure that can be stored and reused. This digital copy eliminates the need to repeatedly print and measure the same charts, reducing manufacturing costs while maintaining color prediction accuracy through computer-based calculations.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent performs preliminary measurement and storage of spectral reflectance data for standard color patches (solid patches, medium color patches, and halftone patches) in advance. This pre-acquired data is stored in a database and reused for multiple overprint predictions, eliminating the need to repeatedly print and measure charts for each prediction task.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If multiple CxF charts are printed for color measurement, then color prediction accuracy is improved, but time consumption increases

Engineering Contradiction:

Improvecolor prediction accuracyVSAvoidtime consumption

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses measured spectral reflectance data from physical CxF charts to create a digital color chart data structure that can be stored and reused. This digital copy eliminates the need to repeatedly print and measure the same charts, reducing time consumption while maintaining color prediction accuracy through computer-based calculations.

Inventive Principle:

Principle #26Copying

3Measurement precision

If manual adjustment of spectral reflectances is performed, then color accuracy is improved, but operational complexity and error rate increase

Engineering Contradiction:

Improvecolor accuracyVSAvoidoperational complexity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces manual adjustment of spectral reflectances with automated computer-based calculations. The system uses measured spectral data and overprint coefficients to automatically compute predicted spectral reflectances for overprinted colors, eliminating manual intervention and its associated errors while maintaining high accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-correction by automatically comparing predicted overprint colors with actual measurements and adjusting overprint coefficients accordingly. This automated feedback mechanism eliminates the need for manual adjustment while improving color accuracy through iterative optimization.

Inventive Principle:

Principle #25Self-service

4Loss of information

If physical CxF charts are printed and measured, then spectral reflectance data is obtained, but cost and time increase

Engineering Contradiction:

Improvespectral reflectance dataVSAvoidtime consumption

Core Design Contradiction:

Loss of informationVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses measured spectral reflectance data from physical CxF charts to create a digital color chart data structure that can be stored and reused. This digital copy eliminates the need to repeatedly print and measure the same charts, reducing time consumption while maintaining color prediction accuracy through computer-based calculations.

Inventive Principle:

Principle #26Copying

Data Source

PatentEP3979614B1Color chart data correction method and color chart data correction program

Publication Date: 2025.12.03 SCREEN HOLDINGS CO LTD

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AI summary

First, an operator adjusts dot percents of halftone patches, so that an input dot percent and an output dot percent are associated for each halftone patch (S401). Next, spectral reflectances of each halftone patch in color chart data are corrected, so that the spectral reflectances corresponding to the output dot percent are associated with the input dot percent for each halftone patch (S402). Finally, a display is shown based on the corrected color chart data (S403).