Optical Comparison of Decorative Samples Using Spectral Interference

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Solution Overview

Problem

Current methods for comparing decorative patterns with non-uniform structures and colors, such as wood decors, lack a satisfactory automated solution, requiring precise matching of color and quality between original and repeated prints, and are limited by the need for identical spatial resolution and wavelength ranges in hyperspectral images.

Innovation Solution

An integral method using diffuse light illumination and a spectrometer with a diffraction grating to capture high-resolution interference spectra, allowing for precise comparison of decorative sections by overlaying reference and actual images, enabling reliable identification of similarity or identity despite non-uniformity in structure and color.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pixel-oriented statistical methods are used to compare decorative patterns, then color comparison can be performed, but the method fails to account for spatial structure and grain patterns which are critical for non-uniform decors

Engineering Contradiction:
Improvecolor comparison precisionVSAvoidspatial structure information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent divides the decorative pattern into multiple evaluation areas (first, second, third areas) with different weighting factors. By segmenting the pattern and assigning different weights to different regions, the method preserves spatial structure information while performing color comparison, resolving the contradiction between color precision and spatial information retention

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by assigning different evaluation weights to different spatial regions of the decorative pattern. Certain areas (e.g., grain patterns, borders) receive higher weights while others receive lower weights, allowing the method to prioritize spatially critical regions in the comparison while maintaining overall color accuracy

Inventive Principle:
Principle #3Local quality

2Measurement precision

If hyperspectral imaging is used to capture detailed wavelength information, then spectral resolution is improved, but the requirement for identical spatial resolution and wavelength ranges between reference and actual images complicates the comparison process

Engineering Contradiction:
Improvespectral resolutionVSAvoidimage matching complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts specific wavelength ranges (first, second, third wavelength ranges) from the hyperspectral data and assigns them to different evaluation areas. By extracting and selectively evaluating specific spectral bands rather than comparing entire hyperspectral cubes, the method reduces the complexity of matching while maintaining spectral resolution

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transforms the comparison problem by changing parameters from requiring identical spatial resolution and wavelength ranges to using weighted spectral integrals over defined wavelength ranges. This parameter transformation allows flexible comparison of hyperspectral data without strict matching requirements

Inventive Principle:
Principle #35Parameter changes

3Productivity

If automated comparison methods are implemented for decorative patterns, then productivity increases, but achieving satisfactory overall satisfaction for non-uniform decors with varying grain and tone remains unmet

Engineering Contradiction:
Improvecomparison automationVSAvoiddecor quality matching
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent performs preliminary actions by pre-defining evaluation areas and weighting factors based on the specific requirements of decorative pattern comparison. The method pre-processes images by dividing them into weighted regions and pre-defines wavelength ranges, enabling automated comparison that is tailored to the specific needs of decor quality assessment

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary weighted evaluation function that mediates between automated processing and quality requirements. The weighting factors act as intermediaries that allow the automated system to prioritize certain spatial and spectral characteristics over others, achieving both automation and reliability

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables highly precise and efficient comparison of decorative patterns with non-uniform structures and colors, ensuring accurate matching of color and structure between original and repeated prints, even with varying wood grain and tone, through high-resolution spectral analysis and automated alignment.

Implementation Method 1

a spectrometer (23) with a diffraction grating (23') to capture high-resolution interference spectra

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

capture high-resolution interference spectra

Methodology Applied
Scientific EffectInterference: Interference

Implementation Method 3

using a scattered light generating device, in particular an integrating sphere (11), to illuminate a section (A1, A2, A3) to be examined

Methodology Applied
Scientific EffectDiffuse light illumination: Scattering

Data Source

PatentEP2409125B1Method and device for carrying out an optical comparison between at least two samples, preferably by comparing sections that can be selected
Publication Date: 2019.07.17 SCHATTDECOR AG
  • EP2409125B1 patent drawingFigure 1
  • EP2409125B1 patent drawingFigure 2
  • EP2409125B1 patent drawingFigure 3

AI summary

An improved method and an improved device for carrying out an optical comparison between at least two samples, preferably by comparing sections that can be selected, is characterized by the following characteristics: the sample (UR, LE, I) that is to be examined and is characterized by a non-uniformity in the structure and/or color is illuminated by diffused light; from the light reflected by the sample (UR, LE, I) to be examined, an interference spectrum is created by means of a spectrometer; the interference spectrum created by the spectrometer is depicted on a camera; the interference spectrum obtained in this way and/or values of the sample (I) to be examined derived therefrom are used as sample values which are compared to sample values of a reference sample (UR, LE) obtained accordingly.