Color Measuring Device Using Camera-Based Matrix Conversion
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Solution Overview
Problem
Conventional color reproduction technologies in image forming apparatuses face challenges in achieving stable color reproducibility due to variations in ink ejection amounts and device-specific characteristics, leading to increased costs and distortion errors, especially when sample data points are unevenly distributed.
Innovation Solution
A color measuring device that includes an obtaining unit for RGB value measurement, a reference value storage unit, a reference-value linear transformation matrix calculating unit, an imaged colorimetric value calculating unit, a patch selecting unit, an RGB selecting unit, a selection-RGB-value linear transformation matrix calculating unit, and a colorimetric value converting unit to adjust color image data based on calculated transformation matrices, ensuring stable color reproduction with reduced distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional color measurement methods using spectrometers are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a camera to capture images of color patches and creates a digital copy of the color information, replacing the need for expensive spectrometers. The camera captures RGB values which are then processed to obtain colorimetric values, achieving a cost-effective alternative to traditional spectrometric measurement.
Solution Approach 2:
The patent replaces the optical mechanical system of a spectrometer with a digital imaging system using a camera. Instead of physically measuring light spectrum, the system uses image capture and digital processing to derive color information, simplifying the measurement device while maintaining precision.
2Measurement precision
If frequent color calibration updates are performed to maintain color reproducibility, then color measurement precision is improved, but loss of time and productivity decrease
Solution Approach 1:
The patent performs preliminary action by capturing images of color patches and calculating transformation matrices in advance, before actual color measurement is needed. The reference color patches are measured and stored, and the transformation matrices are pre-computed, so that when color measurement is required, the system can directly use the pre-prepared data without time-consuming recalibration.
Solution Approach 2:
The patent establishes a continuous reference framework where color patches are captured and transformation matrices are calculated as part of an ongoing calibration process. This continuous preparation ensures that color measurement can be performed continuously without interruption for recalibration, maintaining productivity while ensuring color accuracy.
3Device complexity
If color conversion is performed using local space data only, then device complexity is reduced, but measurement precision deteriorates due to distortion errors
Solution Approach 1:
The patent segments the color space into multiple regions by selecting multiple reference color patches with different color characteristics. Instead of using a single local space, the system divides the color measurement task into multiple segments, each with its own reference patches and transformation matrices, thereby improving overall accuracy without excessive complexity.
Solution Approach 2:
The patent applies local quality by selecting reference color patches that are locally representative of specific color regions. Each reference patch is chosen to represent a particular color characteristic, and the transformation matrices are calculated based on local relationships between reference patches and measured patches, ensuring high precision for each local color region while maintaining overall system simplicity.
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 solution enables stable color reproduction with reduced distortion at lower costs by accurately converting RGB values to device-independent colorimetric values, addressing variations in ink ejection and device characteristics without the need for frequent updates or expensive spectrometers.
Implementation Method 1
an imaging unit that captures a subject being a color measurement object or a reference color patch
Data Source
AI summary
A color measuring device includes a unit configured to calculate a reference-value matrix for converting imaged reference RGB value of a reference color patch a reference colorimetric value of the reference color patch; a unit configured to convert a color-measurement RGB value of a color measurement object into an imaged colorimetric value of the color measurement object by using the corresponding reference-value matrix; a unit configured to select reference color patches of which the reference colorimetric values each have a close distance from the imaged colorimetric value in the predetermined color space; a unit configured to select, as selection RGB values, the imaged reference RGB values of the selected patches; a unit configured to calculate a selection-RGB-value matrix for converting the selection RGB values into the reference colorimetric values; and a unit configured to convert the color-measurement RGB value into a colorimetric value by using the selection-RGB-value matrix.