Contactless Wrist Size Estimation Through Iris-Referenced Imaging

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Solution Overview

Problem

There is a need for an improved method to determine wrist size without the use of a wrist-sizing tool, as not everyone has access to a tape measure.

Innovation Solution

A system and method that uses a computing device to capture images of a user's hand and face, measuring iris diameter, pupillary distance, and wrist width to estimate wrist size, utilizing equations based on actual iris diameter and pupillary distance values to calculate the actual wrist circumference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a tape measure is used to measure wrist size, then measurement precision is improved, but device complexity and accessibility are worsened because not everyone has access to a tape measure

Engineering Contradiction:
Improvewrist size measurementVSAvoidmeasuring tool requirement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses a 2D image copy of the wrist and face instead of direct physical measurement with a tape measure. The system captures an image of the wrist next to the face and uses image processing to measure wrist width based on known facial dimensions, eliminating the need for physical measuring tools.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical tape measure with an optical imaging system. Instead of using a physical measuring tool, the system uses a camera to capture images and computational algorithms to derive measurements, substituting mechanical measurement with optical and computational methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a tape measure is used to measure wrist size, then measurement precision is improved, but ease of operation is worsened because the method requires physical measuring tools and steps

Engineering Contradiction:
Improvewrist size measurementVSAvoidmeasurement process
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system performs the measurement process automatically without requiring user intervention for physical measurement. The user simply needs to position their wrist next to their face in a photo, and the system automatically captures the image, processes it, and calculates the wrist size, making the process much easier and more accessible.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical measurement with automated optical imaging and computational analysis. The system automatically captures images, identifies wrist and face regions, and calculates measurements based on geometric relationships, eliminating the need for manual tape measuring operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If image-based measurement is used, then ease of operation is improved, but measurement precision may be worsened due to potential inaccuracies in image-based estimation

Engineering Contradiction:
Improvemeasurement processVSAvoidwrist size measurement
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent uses the face as an intermediary reference object with known dimensional characteristics. By measuring the face in the same image and using established relationships between facial dimensions and wrist size, the system achieves accurate wrist measurement without direct contact or physical measurement tools.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system transforms the measurement problem from direct physical measurement to a computational parameter estimation problem. By capturing geometric parameters from the image (wrist width in pixels, face width in pixels) and using known relationships between these parameters and actual dimensions, the system accurately estimates wrist size.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4246470B1Systems and methods for contactless estimation of wrist size
Publication Date: 2025.10.29 PERFECT MOBILE CORP
  • EP4246470B1 patent drawingFigure 1
  • EP4246470B1 patent drawingFigure 2
  • EP4246470B1 patent drawingFigure 3

AI summary

A computing device prompts a user to place the user's hand including a wrist next to a facial region of the user. The computing device obtains an image depicting the facial region and a wrist of the user. The computing device measures a diameter of an iris in the facial region depicted in the image and measures a width of a wrist of the hand depicted in the image. The computing device estimates an actual wrist width of the user's hand based on an actual iris diameter, the measured diameter of the iris in the facial region depicted in the image, and the measured width of the wrist of the hand depicted in the image.