Skin Color Chart Layout for Face Authentication Lighting Limits

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Solution Overview

Problem

Existing skin color charts used for face authentication environment determination fail to accurately assess environments where blocked-up shadows or blown-out highlights may occur for individuals with skin tones beyond the average Caucasoid or Negroid ranges, leading to inaccurate face authentication.

Innovation Solution

A skin color chart featuring specific skin tone display parts representing the limits of black and white skin tones, along with optional additional display parts for Mongoloid and gray scale references, to accurately determine suitable face authentication environments by preventing shadows and highlights.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a skin color chart with average Caucasoid and average Negroid skin color display parts is used to determine face authentication environment, then the environment assessment is simplified, but face authentication accuracy deteriorates for individuals with skin tones beyond the average ranges

Engineering Contradiction:
Improveskin color chart structureVSAvoidface authentication accuracy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The skin color chart is segmented into multiple display parts representing different skin tone ranges (Caucasoid, Mongoloid, Negroid) with each part showing minimum, average, and maximum skin tones. This segmentation allows comprehensive coverage of diverse skin tones while maintaining a structured, manageable chart format.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each skin color display part is assigned specific local quality characteristics corresponding to different racial groups and skin tone extremes. The chart provides localized color representations for minimum, average, and maximum skin tones within each racial category, enabling precise environment assessment for individuals with various skin tones.

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If the skin color chart includes only average skin color display parts, then the chart is easier to manufacture, but it cannot accurately assess environments for individuals with extreme skin tones

Engineering Contradiction:
Improveskin color chart productionVSAvoidenvironment assessment accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The chart divides skin color representation into discrete segments (minimum, average, maximum skin tones) for each racial group. This segmentation enables systematic manufacturing while ensuring comprehensive coverage of skin tone variations, allowing accurate environment assessment without overly complicating production.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The skin color display parts represent different parameter values of skin tone (minimum, average, maximum) within each racial category. By incorporating these parameter variations, the chart achieves high measurement precision for environment assessment while maintaining a systematic structure that facilitates manufacturing.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If the skin color chart covers a wide range of skin tones, then face authentication accuracy for diverse individuals is improved, but the chart complexity increases

Engineering Contradiction:
Improveskin tone coverageVSAvoidskin color chart structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The chart organizes diverse skin tones into segmented categories by racial group (Caucasoid, Mongoloid, Negroid), with each group containing minimum, average, and maximum skin tone display parts. This segmentation approach achieves wide skin tone coverage while maintaining a structured, manageable chart organization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The skin color chart serves multiple functions simultaneously: it assesses face authentication environments for diverse skin tones, provides reference standards for different racial groups, and enables determination of suitable authentication conditions. This multi-functionality achieves wide adaptability while consolidating multiple assessment capabilities into a single unified chart.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4067845B1Skin color chart and method for preparing same
Publication Date: 2025.12.31 NEC CORP
  • EP4067845B1 patent drawingFigure 1
  • EP4067845B1 patent drawingFigure 2
  • EP4067845B1 patent drawingFigure 3

AI summary

A skin color chart (10) according to an example aspect of the present disclosure includes: a substrate (11); a first skin color display part (BK) configured to show a skin color of a Negroid, the first skin color display part being formed on the substrate (11); and a second skin color display part (WT) configured to show a skin color of a Caucasoid, the second skin color display part being formed on the substrate (11). Lightness L∗ of the first skin color display part (BK) in a CIE L∗a∗b∗ color space satisfies 20≤L∗≤37, and lightness L∗ of the second skin color display part (WT) in the CIE L∗a∗b∗ color space satisfies 74≤L∗≤81.