Metallic Paint Color Specification Using Curved Brightness Models

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Solution Overview

Problem

Existing methods for specifying metallic paint colors from digital images often fail to accurately represent color characteristics due to insufficient sampling points, leading to unnatural color representations and inability to correctly specify desired paint colors.

Innovation Solution

A paint color specifying apparatus that allows designation of highlighted and shaded portions in a digital image, acquires color information, selects texture information, and calculates color characteristics using a correction coefficient to approximate a curve where brightness decreases with reflection angle, ensuring accurate representation of paint color characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple sampling points corresponding to reflection angles and luminances are specified to represent metallic paint color characteristics, then the accuracy of color specification is improved, but the complexity of the system increases due to the need to calculate approximate curves through multiple points

Engineering Contradiction:
Improvecolor specification accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the color characteristic representation into two independent parts: (1) a straight line representing the relationship between reflection angle and luminance for metallic paint colors, and (2) a separate curve representing the color characteristics. This segmentation allows the complex curve to be simplified while maintaining accuracy through the linear component, reducing computational complexity while preserving measurement precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses a curved line to represent the color characteristics of metallic paint colors, which naturally captures the non-linear relationship between reflection angle and luminance. This curved representation simplifies the mathematical model compared to using multiple discrete sampling points and complex curve fitting algorithms, thereby reducing system complexity while maintaining high color specification accuracy.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Measurement precision

If approximate curves are calculated through multiple sampling points to represent color characteristics, then the representation accuracy is improved, but the difficulty of detecting and measuring increases due to complex curve fitting requirements

Engineering Contradiction:
Improvecolor characteristic representation accuracyVSAvoidcurve fitting difficulty
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent separates the color characteristic representation into a straight line component and a curve component. This segmentation simplifies the measurement process by reducing the curve fitting task to a simpler form, making it easier to detect and measure color characteristics while maintaining high representation accuracy through the combined linear and curved models.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameters used in curve fitting by using a simplified curved line model instead of complex polynomial or spline functions that would be required to fit multiple sampling points. This parameter simplification reduces the difficulty of detecting and measuring color characteristics while maintaining accurate representation through the adjusted model parameters.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If only two sampling points are used to calculate color characteristics, then the system complexity is reduced, but the accuracy of representing metallic paint color characteristics deteriorates

Engineering Contradiction:
Improvesystem complexityVSAvoidcolor characteristic accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent employs a curved line to represent color characteristics, which allows accurate representation of metallic paint colors even with limited sampling points. The curved model captures the essential non-linear behavior of metallic paints, maintaining measurement precision without requiring multiple sampling points and complex calculations, thus avoiding increased system complexity.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes the mathematical model from simple linear interpolation between two points to a curved line model. This parameter change enables the system to maintain high color characteristic accuracy with only two sampling points by using the curved model's flexibility to fit the metallic paint color characteristics, thereby avoiding the need for additional sampling points and reducing system complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3605467B1Coating color identifying device, coating color identifying method, coating color identifying program, and computer-readable medium containing coating color identifying program
Publication Date: 2023.08.09 KANSAI PAINT CO LTD
  • EP3605467B1 patent drawingFigure 1
  • EP3605467B1 patent drawingFigure 2
  • EP3605467B1 patent drawingFigure 3

AI summary

A paint color specifying apparatus of the invention includes an image display which causes a display device to display a digital image such that a highlighted portion and a shaded portion of the digital image are able to be designated, a color information acquiring device which acquires color information of the designated highlighted portion and shaded portion, a texture information selection display which causes the display device to display texture information of paint colors such that texture information of a paint color is selectable, a texture information acquiring device which acquires the selected texture information, a color characteristic calculating device which uses a correction coefficient corresponding to the acquired texture information in accordance with the acquired color information and thereby calculates color characteristics of a paint color represented by change in brightness of reflected light according to a reflection angle with respect to incident light, and a paint color specifying device which specifies a paint color in accordance with the calculated color characteristics.