Hybrid Spectra-Camera Calibration for Wideband Colorimeter Precision

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Solution Overview

Problem

Wideband colorimeters provide only approximate tristimulus signals with varying quality, lacking the precision required for accurate colorimetric measurements under arbitrary stimuli and illumination conditions, compared to more expensive narrowband instruments.

Innovation Solution

A hybrid system combining a wideband colorimeter with a narrowband spectrograph, known as a spectra-camera, performs simultaneous testing to achieve accurate calibration of the wideband colorimeter using a mathematical model and correction matrices based on predetermined test patterns, enhancing the accuracy of color measurement outputs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If wideband colorimeters are used for color measurement, then cost-effectiveness and fast data reading are improved, but measurement precision deteriorates

Engineering Contradiction:

Improvecost-effectivenessVSAvoidmeasurement precision

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

A correction matrix derived from spectral measurements acts as an intermediary to transform wideband colorimeter readings into accurate colorimetric values. The correction matrix serves as a mathematical mediator that compensates for the wideband instrument's limitations without requiring the physical complexity of narrowband instrumentation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention transforms the measurement parameters by using spectral data to derive correction factors that adjust the wideband colorimeter's output. By changing the parameter space from direct wideband measurements to corrected values based on spectral characteristics, the system achieves narrowband-level precision with wideband hardware.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If narrowband instruments are used for accurate colorimetric measurement, then measurement precision is improved, but cost and device complexity increase

Engineering Contradiction:

Improvecolorimetric measurement accuracyVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The correction matrix derived from spectral measurements serves as a mathematical intermediary that enables wideband colorimeters to achieve narrowband-level accuracy without requiring the physical complexity of narrowband instrumentation, beam splitters, or rotating filters.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a mathematical copy of the spectral measurement capability through correction matrices. Instead of physically implementing narrowband spectral measurement for every reading, the system captures spectral data once and uses it to generate correction factors that replicate narrowband measurement accuracy across all subsequent wideband measurements.

Inventive Principle:

Principle #26Copying

3Device complexity

If wideband colorimeters approximate tristimulus signals, then device simplicity is improved, but measurement accuracy under arbitrary stimuli deteriorates

Engineering Contradiction:

Improvedevice simplicityVSAvoidtristimulus signal accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The correction matrix acts as a feedback mechanism that compensates for the wideband colorimeter's approximation errors. By incorporating spectral information into the correction process, the system continuously adjusts the tristimulus signal accuracy based on the actual spectral characteristics of the measured stimulus.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The hybrid system significantly improves the accuracy of wideband colorimeter outputs by up to one order of magnitude, achieving precision comparable to narrowband instruments while maintaining the cost-effectiveness of wideband devices.

Implementation Method 1

A hybrid system combining a wideband colorimeter with a narrowband spectrograph, known as a spectra-camera, performs simultaneous testing

Methodology Applied

Scientific EffectSpectrograph spectral separation: Diffraction Grating

Data Source

PatentEP2912421B1High accuracy imaging colorimeter by special designed pattern closed-loop calibration assisted by spectrograph

Publication Date: 2024.05.01 APPLE INC

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AI summary

This specification describes various embodiments that relate to methods for providing a wideband colorimeter that can include more accurate outputs. In one embodiment, a narrowband instrument, such as a spectrometer or spectrograph, can be used for calibration of a wideband colorimeter, so that more accurate outputs can be provided. In one embodiment, an optical test equipment, which consists of both a wideband colorimeter and a narrowband spectrograph, can be used for providing a more accurately calibrated wideband colorimeter. As an example, a spectra-camera, which is a hybrid system consisting of both a wideband colorimeter and a narrowband spectrograph, can be used for simultaneous testing by both the wideband colorimeter and the narrowband spectrograph. By doing simultaneous testing, accurate calibration of the wideband colorimeter can be achieved. This specification further describes a mathematical model to characterize a wideband three channel colorimeter with a narrowband multiple channel spectrometer.