Optical Code Finder Pattern Localization via Edge Transition Verification
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Solution Overview
Problem
Current methods for locating optical codes, such as QR and Aztec codes, face challenges in accurately detecting finder patterns due to interference, distortions, and occlusions, leading to high error rates and incomplete code recognition.
Innovation Solution
A method that determines candidate positions for finder patterns based on edge transitions, verifies these positions using known properties, and employs a combination of geometric operations and verification steps to confirm the presence of the finder pattern, reducing false positives and negatives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods search line by line for edge transitions with strict conditions, then false positive finder patterns are reduced, but partially hidden finder patterns are discarded and codes are overlooked
Solution Approach 1:
The detection process is divided into multiple independent verification stages: initial edge transition detection, candidate position identification, geometric property verification (checking for characteristic 1:1:3:1:1 transition ratios), and final confirmation. This segmented approach allows each stage to focus on specific aspects without being constrained by strict overall conditions.
Solution Approach 2:
The method performs excessive verification by checking multiple geometric properties and transition ratios beyond the minimum required for detection. Candidate positions are verified against multiple criteria including edge transition patterns, finder pattern geometry, and code structure expectations, ensuring high confidence before acceptance.
2Reliability
If tolerance is increased for edge transition conditions, then sensitivity is improved and more codes are detected, but false positive finder patterns increase
Solution Approach 1:
The verification process provides feedback by checking candidate positions against known finder pattern properties. If a candidate position fails verification (e.g., incorrect edge transition ratios or geometric properties), it is rejected. This feedback mechanism allows the system to maintain high sensitivity while filtering false positives through systematic verification.
Solution Approach 2:
The method performs preliminary verification of candidate positions using geometric properties and transition ratios before final acceptance. This preliminary action filters out false positives early in the process, allowing the system to maintain high sensitivity without being overwhelmed by incorrect detections.
3Measurement precision
If machine learning is used for finder pattern detection, then detection accuracy may improve, but hardware requirements and response time increase
Solution Approach 1:
The patent replaces complex machine learning systems with a deterministic geometric verification approach based on known finder pattern properties. Instead of using neural networks or complex algorithms, the system uses simple geometric checks of edge transition ratios and finder pattern structure, achieving high accuracy with minimal hardware requirements.
Solution Approach 2:
The method uses simple, computationally inexpensive verification checks that can be performed rapidly with basic hardware. Rather than investing in complex machine learning infrastructure, the system employs lightweight geometric property checks that are fast to execute and require minimal computational resources.
Data Source
AI summary
A method for locating an optical code, on the basis of a finder pattern of the optical code, in an image having a plurality of pixels, the method comprising the steps ofdetermining at least one candidate position for the finder pattern on the basis of edge transitions along at least one line through the image;determining a final position of the finder pattern in a vicinity of the candidate position; andverifying the final position, i.e. verifying that the image comprises the finder pattern in the final position, using a known property of the finder pattern.