Sclera-Based Skin Tone Detection Under Variable Lighting

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Solution Overview

Problem

Existing methods for determining skin tone require a standardized color palette, which is often not readily available, leading to incorrect skin tone determination due to varying lighting conditions and camera imperfections, resulting in inaccurate cosmetic product recommendations.

Innovation Solution

A system and method that utilizes the sclera of the eye to normalize pixel values, allowing for accurate skin tone determination without the need for a physical color palette by identifying a representative pixel value from the sclera and normalizing skin region pixel values, then matching this value to a palette of skin tones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a standardized color palette is placed next to the customer for calibration, then the skin tone determination accuracy is improved, but the ease of operation deteriorates because the palette is not always readily available and makes the task time-consuming and tedious

Engineering Contradiction:
Improveskin tone determination accuracyVSAvoidease of operation
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system uses the user's own eye sclera (white part of the eye) as the reference standard for color calibration, eliminating the need for external standardized color palettes. The sclera naturally serves as a white reference that is always available when the user's face is captured, making the calibration process automatic and convenient without requiring the user to manually position or provide a color chart.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention introduces the sclera as an intermediary reference element between the lighting conditions and the skin tone measurement. By using the sclera's known white color property as a mediator, the system can calculate color temperature and compensate for lighting effects, thereby determining accurate skin tone without needing external calibration tools.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If traditional methods are used without sclera normalization, then the device complexity is reduced, but the measurement precision deteriorates due to incorrect skin tone determination from varying lighting conditions and camera imperfections

Engineering Contradiction:
Improvedevice complexityVSAvoidskin tone determination accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The system automatically uses the user's sclera as an internal reference standard that is always present in facial images. This self-contained approach eliminates the need for external calibration equipment, maintaining simple device architecture while significantly improving measurement accuracy through automatic color temperature calculation and normalization.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the approach from direct skin tone measurement to indirect measurement through sclera-based color temperature calculation. By first determining the color temperature from the sclera's white reference and then normalizing the skin tone values accordingly, the system achieves higher precision without adding complex hardware, only computational steps.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If images are taken under varying lighting conditions without calibration, then the ease of operation is improved, but the reliability deteriorates because incorrect colors lead to incorrect skin tone determination and wrong cosmetic product recommendations

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system automatically performs calibration using the user's own sclera as a reference, requiring no manual intervention or special preparation from the user. This maintains ease of operation while ensuring reliability across varying lighting conditions, as the sclera-based normalization compensates for color temperature differences automatically.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention implements a feedback mechanism where the sclera's color information is used to calculate the ambient lighting conditions, which then feeds back into the skin tone determination process. This closed-loop approach ensures that skin tone measurements are always normalized to account for lighting variations, maintaining high reliability without complicating the user experience.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3979212B1A system and method for determining a skin tone
Publication Date: 2026.03.11 REVIEVE OY
  • EP3979212B1 patent drawingFigure 1~2
  • EP3979212B1 patent drawingFigure 3~4
  • EP3979212B1 patent drawingFigure 5~6

AI summary

A system for determining a skin tone of a user. Herein, a server arrangement obtains an input image capturing at least a face of the user; analyze the input image to identify at least one first region of the input image that corresponds to a sclera of the user; determine a representative pixel value of the sclera; determine at least one second region of the input image that corresponds to a skin of the user; normalize pixel values of pixels in the at least one second region; determine a representative pixel value of the skin from the normalized pixel values of the pixels in the at least one second region; and select, from amongst a palette of skin tones, a skin tone whose pixel value matches with the representative pixel value of the skin. Herein, the selected skin tone is determined as the skin tone of the user.