2D Barcode Module Pixel Distribution for OCR Detection

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Solution Overview

Problem

Current OCR thresholding algorithms are not well-suited for reading two-dimensional barcodes in postal indicia, leading to data loss and damage to finder patterns due to insufficient ink optical density and reflectivity variation, causing modules to be misinterpreted as background.

Innovation Solution

The method involves printing two-dimensional barcodes with modified darkened modules that include a combination of printed and non-printed pixels along their edges, ensuring that the OCR thresholding window captures sufficient reflectivity variation to treat the modules as foreground, thereby preventing data loss and damage to the finder patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If standard darkened modules are printed with uniform pixel density, then the barcode data is accurately represented, but the OCR thresholding window fails to detect sufficient reflectivity variation and misinterprets modules as background

Engineering Contradiction:

ImproveOCR reading accuracyVSAvoidmodule detection reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies local quality by creating non-uniform pixel distribution within darkened modules, specifically reducing pixel density at corner locations while maintaining higher density in central regions. This local variation in pixel quality creates the reflectivity variation needed for OCR detection without compromising the overall data representation, as the module remains predominantly darkened.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of pixel density distribution within modules by introducing controlled variations, specifically reducing pixel density at corner positions. This parameter change creates sufficient reflectivity variation that allows OCR thresholding windows to detect the modules as foreground elements while preserving the binary data representation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If ink optical density is increased to improve module visibility, then modules are more easily detected, but the cost of printing increases and the ink consumption increases

Engineering Contradiction:

Improvemodule detection reliabilityVSAvoidink consumption

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent uses local quality by concentrating pixel density variations at specific locations (corners) rather than uniformly increasing ink density across the entire module. This approach creates the necessary reflectivity variation for detection while minimizing overall ink consumption, as only specific pixel locations within each module are affected.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If the barcode is printed with high contrast to improve scanning accuracy, then reading precision improves, but the finder pattern becomes vulnerable to damage from thresholding algorithms

Engineering Contradiction:

Improvescanning accuracyVSAvoidfinder pattern damage

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by pre-modifying the finder pattern structure to counteract the harmful effects of OCR thresholding algorithms. Specifically, the finder pattern modules are designed with reduced pixel density at corner positions, which prevents the thresholding algorithm from misinterpreting them as background, thereby protecting the finder pattern from damage before the scanning process occurs.

Inventive Principle:

Principle #9Preliminary anti-action

4Ease of manufacture

If uniform pixel distribution is used in darkened modules, then manufacturing simplicity is maintained, but data loss occurs due to insufficient reflectivity variation for OCR processing

Engineering Contradiction:

Improveprinting process simplicityVSAvoidbarcode data loss

Core Design Contradiction:

Ease of manufactureVSLoss of information

Solution Approach 1:

The patent implements local quality by introducing non-uniform pixel distribution specifically at corner locations of darkened modules, while maintaining uniform distribution in other regions. This targeted approach creates the necessary reflectivity variation for OCR processing without requiring a complete overhaul of the printing process, thus maintaining manufacturing simplicity while preventing data loss.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7424975B2Method for printing two dimensional barcodes to reduce reading errors

Publication Date: 2008.09.16 PITNEY BOWERS INC

AI summary

A method of printing modules for a two dimensional barcode that includes printing a pixel at a plurality of the pixel locations included in the inner portion of the darkened module, and printing a pixel at less than all of the pixel locations of the outer boundary of the darkened module. Various embodiments are contemplated, such as, without limitation, methods that print darkened modules having four light corners, three light corners, two light corners, one light corner, and/or one light edge. Also, a method of printing a two dimensional barcode having a finder pattern wherein the inner edge of the finder pattern is light, meaning that is does not include any printed pixels at the pixel locations along the inner edge.