Adaptive Sampling Pattern for Distorted Optical Codes
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Solution Overview
Problem
Conventional methods for reading optical codes fail when codes are distorted by uneven backgrounds, such as non-planar surfaces, as they are not designed to handle complex deformations, leading to reading errors, especially in applications like soft packaging where existing error correction mechanisms reach their limits.
Innovation Solution
A method and apparatus that generate a sampling pattern of sampling points adapted to the distortions of the background, allowing for accurate reading of optical codes by compensating for deformations, even without prior knowledge of the background geometry, by iteratively growing the sampling pattern from a finder pattern and shifting points to center them within code modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction mechanisms (e.g., Reed-Solomon) are used to read distorted codes, then reading reliability is maintained for flat codes, but reading fails completely when complex deformations occur on non-planar surfaces
Solution Approach 1:
The patent segments the code reading process into multiple sampling points arranged in a sampling pattern that corresponds to the distorted geometry of the code. Instead of attempting to read the entire distorted code as a single unit, the method divides the code into multiple sampleable regions, allowing each to be read independently despite overall distortion
Solution Approach 2:
The patent applies local quality by creating a sampling pattern that adapts to local distortions in different parts of the code. Each sampling point is positioned to account for local geometric variations, allowing the reading system to handle non-uniform deformations across the code surface
2Shape
If perspective transformation methods are used to correct imaging errors, then oblique perspective distortion is reduced, but individual geometric distortions within the code on non-planar surfaces remain uncorrected
Solution Approach 1:
The patent performs preliminary action by establishing a sampling pattern that anticipates and accounts for code distortions before the actual reading process. The sampling points are pre-positioned based on expected distortion patterns, allowing the system to compensate for geometric variations in advance rather than attempting post-processing correction
3Reliability
If 3D surface detection is used to write codes on curved surfaces, then code readability on regular geometries is improved, but the process requires considerable effort and only works for certain regular geometries
Solution Approach 1:
The patent uses copying by creating a sampling pattern that replicates the distorted geometry of the code. Instead of detecting and correcting the actual 3D surface, the method creates a 2D sampling pattern that copies the apparent distortion seen in the image, allowing standard 2D reading techniques to succeed on distorted surfaces
4Measurement precision
If a convex envelope is used to detect global geometric structure, then small regular distortions can be handled, but the method fails when global geometry contains insufficient information such as on wrinkled plastic covers
Solution Approach 1:
The patent applies dimensionality change by moving from attempting to detect global 3D surface geometry to working directly with 2D image data. The sampling pattern is defined in the 2D image plane rather than attempting to map the 3D surface, allowing the system to handle arbitrary distortions without requiring 3D surface information
Data Source
AI summary
A method for reading optical codes (12) with distortions caused by an uneven background of the code (12), the method comprising the steps of acquiring image data including the code (12), locating a region including the code (12) in the image data, and reading the code content of the code (12) from image data in the region, wherein the code (12) is read from image data at sampling points arranged in a sampling pattern corresponding to the distortions.