Printer Characterization Using Tone Value Model Interpolation

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Solution Overview

Problem

The process of color separation for printing is complex and labor-intensive, requiring the definition and printing of a printer characterization target, regularization of measured colors, calculation of a printer model, and inversion for look-up table entries, which is time-consuming and requires significant skill.

Innovation Solution

A method that reduces the number of color patches needed for printer characterization by using a tone value model to predict color values, allowing for interpolation between known endpoints, and utilizing a reduced printer characterization target with a subset of patches to calculate missing values, thereby simplifying the process of obtaining a printer model.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a complete printer characterization target with all color patches is printed and measured, then measurement precision and completeness of printer model are improved, but loss of time and labor intensity increase significantly

Engineering Contradiction:

Improveprinter model accuracyVSAvoidcharacterization time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The complete printer characterization process is segmented into two phases: (1) printing and measuring only the essential color patches (CMYK primaries and black) to obtain baseline data, and (2) calculating the colors of non-printed patches using tone value models and interpolation algorithms. This segmentation eliminates the time-consuming measurement step for non-essential patches while maintaining model accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Tone value models are pre-calculated for each ink channel based on the measured primary color patches. These models establish the relationship between digital tone values and measured colors, enabling subsequent interpolation to predict colors of unmeasured patches without requiring additional printing or measurement operations.

Inventive Principle:

Principle #10Preliminary action

2Loss of information

If all color patches are printed for characterization, then completeness of color data is improved, but complexity of the characterization process increases

Engineering Contradiction:

Improvecolor data completenessVSAvoidcharacterization process complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The invention extracts only the essential color patches (CMYK primaries and black) from the complete characterization target, printing and measuring only these critical patches. The colors of all other patches are derived through calculation using tone value models and interpolation, thereby simplifying the physical characterization process while maintaining data completeness.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of physically printing and measuring all color patches, the invention creates virtual copies of the complete characterization data by calculating the colors of non-printed patches based on the measured primary patches and established tone value models, thus obtaining complete color information without the complexity of measuring every patch directly.

Inventive Principle:

Principle #26Copying

3Productivity

If a reduced set of color patches is used, then productivity and efficiency are improved, but measurement precision may deteriorate

Engineering Contradiction:

Improvecharacterization speedVSAvoidcolor accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The invention changes the approach from direct measurement of all patches to a hybrid method where primary patches are measured and secondary patches are calculated using tone value models. This parameter change in the characterization methodology maintains color accuracy by using mathematically robust interpolation based on the measured primary data, while significantly improving productivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Tone value models serve as intermediaries between the measured primary color patches and the calculated colors of non-printed patches. These models establish the functional relationship between digital tone values and measured colors, enabling accurate prediction of unmeasured patch colors without direct measurement, thus maintaining precision while improving efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9906690B2Method for characterizing a printer

Publication Date: 2018.02.27 ECO3 BV

AI summary

A standard printer characterization target is printed with a reference printer and measured. From the measured data, a model is derived that describes for each ink the behavior of each individual ink in combination with different combinations of the other inks. In order to reduce the complexity for obtaining a printer model of a second printer, a second target is printed that includes only a subset of the color patches in the standard printer characterization target. With the model and interpolation, it is possible to reconstruct colorimetric data for missing color patches in the reduced target.