Video-Based Biometric Passport Photos with Background Correction

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Solution Overview

Problem

Existing methods for determining passport photo data for security documents are inefficient and prone to errors, particularly in capturing images with unsuitable backgrounds, necessitating additional single-image recordings and complex post-processing.

Innovation Solution

A method and device that utilize video image recording to capture a sequence of portrait images, adjusting illumination conditions, and applying background correction to ensure compliance with multiple verification criteria, including background requirements, thereby generating a digital biometric passport photo directly from video images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If video image recording is used to capture portrait images, then the efficiency of passport photo generation is improved, but the susceptibility to errors increases due to unsuitable backgrounds

Engineering Contradiction:
Improvepassport photo generation efficiencyVSAvoidpassport photo quality
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs preliminary analysis of video frames to identify suitable portrait images before final processing. It pre-checks multiple criteria including background suitability, lighting conditions, and facial visibility to select optimal frames for passport photo generation, preventing errors before they occur.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms by continuously monitoring captured frames against verification criteria. When unsuitable backgrounds or conditions are detected, the system provides feedback to adjust capture parameters or select alternative frames, ensuring reliable passport photo quality while maintaining high efficiency through automated iterative refinement.

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If additional single-image recordings are performed to correct background issues, then the passport photo quality is improved, but the processing time and complexity increase

Engineering Contradiction:
Improvepassport photo qualityVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system maintains continuous video recording throughout the process, continuously analyzing and selecting suitable frames rather than stopping for separate single-image shots. This continuous action allows background correction to be performed by selecting different moments from the ongoing video stream, eliminating time loss while maintaining photo quality.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system captures and analyzes more video frames than strictly necessary, examining multiple consecutive frames to ensure at least one meets all criteria including background requirements. This excessive sampling approach ensures quality without requiring additional dedicated recording sessions, as suitable frames are found within the already-captured video sequence.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If multiple verification criteria are applied to ensure compliance, then the passport photo reliability is improved, but the device complexity increases

Engineering Contradiction:
Improvepassport photo verification accuracyVSAvoidprocessing system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The verification process is segmented into multiple independent criteria checks: background suitability, lighting conditions, facial visibility, pose verification, and image quality assessment. Each criterion is evaluated separately using dedicated algorithms, allowing complex verification to be broken down into manageable, modular components that can be processed efficiently.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs self-verification by automatically checking captured frames against all required criteria without external intervention. The embedded processing unit independently evaluates each frame, selects suitable candidates, and determines compliance with passport photo standards, reducing the need for complex external verification equipment or manual review processes.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4184456B1Method and device for determining a digital biometric template for a security document and method for personalizing a security document
Publication Date: 2025.10.22 BUNDESDRUCKEREI GMBH
  • EP4184456B1 patent drawingFigure 1
  • EP4184456B1 patent drawingFigure 2

AI summary

The invention relates to a method for determining passport photo data representing a digital biometric passport photo for a security document (1), comprising: recording a sequence of portrait images of a person (4) by means of video image recording at a frame rate using a video image recording device (2), wherein the person (4) is illuminated by means of a lighting device (7); storing the respective portrait image data for the portrait images from the video image recording; and determining passport photo data representing a digital biometric passport photo of the person (4). The determination of passport photo data comprises the following: determining a first portrait image from the sequence of portrait images, which was recorded according to the recording conditions and meets several test criteria for a digital biometric passport photo for a security document (1), but not with regard to a background test criterion for the digital biometric passport photo.Determining a lighting characteristic applied by means of the lighting device (7) when taking the first portrait image, indicating at least one illuminance; taking further portrait images of the person (4) using the video image recording device (2) and the lighting device (7), maintaining the shooting conditions, wherein the further portrait images comprise a first further portrait image taken using the illuminance and a second further portrait image taken using an illuminance that differs from the illuminance; determining a suitable portrait image from the further portrait images that meets the multiple test criteria and the background test criterion for the digital biometric passport photo;and generating passport photo data using portrait image data assigned to the appropriate portrait image. Furthermore, a method for personalizing a security document and a device for determining passport photo data are disclosed.