Document Viewing Angle Feature Detection via Image Difference

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Solution Overview

Problem

The detection of viewing angle-dependent features in documents, such as holograms, is typically time-consuming and inefficient when performed manually, necessitating an automated solution for verification and authentication.

Innovation Solution

A method involving an image camera that captures images of a document in different spatial layers, determining image differences between these captures to efficiently detect viewing angle-dependent features, which can include holograms or other angle-dependent representations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual detection of viewing angle-dependent features is performed, then verification accuracy can be maintained, but detection time increases significantly

Engineering Contradiction:
Improveverification accuracyVSAvoiddetection time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the manual mechanical inspection process with an automated image processing system. The camera captures images from multiple spatial orientations, and computer algorithms automatically detect viewing angle-dependent features by comparing image differences, eliminating the need for manual visual inspection while maintaining verification accuracy.

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

Solution Approach 2:

The system performs preliminary actions by capturing multiple images from different spatial orientations before the actual detection process. These pre-captured images are then processed to identify viewing angle-dependent features, allowing the system to prepare verification data in advance and reduce detection time.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If automated detection system is implemented, then detection speed increases, but system complexity increases

Engineering Contradiction:
Improvedetection speedVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent employs a universal image processing approach that can detect various types of viewing angle-dependent features (holograms, security threads, color-shifting elements) using the same system architecture. The camera and image processing algorithms serve multiple verification functions, reducing the need for specialized equipment for each feature type.

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

Solution Approach 2:

The system adds the spatial orientation dimension to the detection process by capturing images from multiple angles. This dimensional approach allows the system to identify viewing angle-dependent features through image comparison, transforming a complex visual inspection task into a manageable computational problem based on spatial relationships.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Measurement precision

If multiple images from different spatial orientations are captured, then detection accuracy of viewing angle-dependent features improves, but data processing volume increases

Engineering Contradiction:
Improvedetection accuracyVSAvoiddata processing volume
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The system extracts only the relevant information from the captured images by comparing image differences between multiple spatial orientations. Instead of processing all image data equally, the algorithm identifies and extracts specific regions where viewing angle-dependent features are located, reducing the effective data processing volume while maintaining detection accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3158543B1Method for detecting a viewing angle dependent feature of a document
Publication Date: 2021.10.13 BUNDESDRUCKEREI GMBH
  • EP3158543B1 patent drawingFigure 1
  • EP3158543B1 patent drawingFigure 2
  • EP3158543B1 patent drawingFigure 3

AI summary

The invention relates to a method (100) for detecting a viewing-angle-dependent feature of a document using a photographic camera, wherein the viewing-angle-dependent feature has viewing-angle-dependent representations, with capture (101) of a first image of the document by the photographic camera in a first spatial orientation of the document relative to the photographic camera, in order to obtain a first document image, capture (103) of a second image of the document by the photographic camera in a second spatial orientation of the document relative to the photographic camera, in order to obtain a second document image, and capture (105) of an image difference between the first document image and the second document image, in order to detect the viewing-angle-dependent feature of the document.