Optical Code Reading with Schema-Guided ROI Correction

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Solution Overview

Problem

Existing optical code reading systems face challenges in achieving high read rates due to segmentation errors caused by code defects such as reflections or rotations, leading to incomplete partial reads and increased corrective actions.

Innovation Solution

A method that uses pre-defined or trained schemas to refine the area of interest by comparing read characters to expected character patterns, adjusting the size and orientation of the ROI based on schema expectations, and creating a new area of interest to encompass the entire optical code, thereby eliminating the need for repeated segmentation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If segmentation is performed multiple times with different parameters or at different resolution levels, then segmentation accuracy is improved, but processing time and computational effort increase significantly

Engineering Contradiction:
Improvesegmentation accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary segmentation to identify an initial ROI, then uses schema validation to detect potential segmentation errors before final code reading. This preliminary detection allows for targeted correction without requiring complete re-segmentation, thus improving accuracy while minimizing additional processing time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the read result is validated against the schema, and if errors are detected, the system feeds back to adjust the ROI and re-read only the affected portion. This feedback loop enables error correction without repeating the entire segmentation process, resolving the contradiction between accuracy and processing time.

Inventive Principle:
Principle #23Feedback

2Reliability

If the ROI is enlarged to encompass the entire code, then complete code reading is achieved, but processing time and computational resources increase

Engineering Contradiction:
Improvecomplete code readingVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial action by only enlarging the ROI to the extent necessary to include the complete code, rather than processing the entire image. The schema validation helps determine the minimum required ROI size, enabling complete code reading with minimal additional processing overhead.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent dynamically adjusts the ROI parameters (position and size) based on schema validation results and detected code characteristics. By changing only the necessary parameters rather than reprocessing the entire image, the system achieves complete code reading while minimizing processing time.

Inventive Principle:
Principle #35Parameter changes

3Speed

If traditional image processing algorithms are used for segmentation, then processing speed is maintained, but segmentation errors occur with defective codes

Engineering Contradiction:
Improveprocessing speedVSAvoidsegmentation accuracy
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent introduces schema validation as an intermediary step between traditional image processing segmentation and code reading. This intermediary layer detects segmentation errors without requiring complex alternative segmentation algorithms, maintaining processing speed while improving segmentation accuracy through intelligent error detection and correction.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces purely mechanical/image-based segmentation approaches with a hybrid system that incorporates logical/schema-based validation. This substitution enables the system to detect and correct segmentation errors that traditional algorithms would miss, improving accuracy without significantly increasing processing time.

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

Data Source

PatentEP4571571B1Reading an optical code
Publication Date: 2026.02.04 SICK AG
  • EP4571571B1 patent drawingFigure 1~2
  • EP4571571B1 patent drawingFigure 3
  • EP4571571B1 patent drawingFigure 4~5

AI summary

A method is provided for reading an optical code (20) which encodes a message having a character string with a plurality of characters, comprising the steps of recording image data with the optical code (20), segmenting the image data in order to find a region of interest (30) with the optical code (20), evaluating the image data within the region of interest (30) in order to read the message, comparing the read characters of the message with at least one schema which, for at least one position of the message, contains an expectation about a character at this position of the optical code (20) to be read, and thereby determining a schema which matches the message and which matches the read message in a minimum proportion of the characters.In this case, a size of a region of interest is determined from the scheme, into which an optical code (20) matching the scheme fits, and a new region of interest (32) of this size is generated.