OCR for Non-Coplanar Documents via Region-Specific Coordinate Transformations

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Solution Overview

Problem

Existing optical character recognition (OCR) methods face challenges in accurately recognizing text from images of documents with non-coplanar regions, such as bent or folded pages, due to inadequate coordinate transformations, leading to incorrect character recognition and degraded OCR quality.

Innovation Solution

The method involves identifying base points within each planar region of a document image, determining separate coordinate transformations for each region, and applying boundary corrections to improve the accuracy of coordinate transformations, allowing for the identification of symbol sequences across multiple images and producing a median symbol sequence for improved OCR text representation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single coordinate transformation is used for the entire document image, then the transformation process is simple, but OCR accuracy deteriorates for documents with non-coplanar regions

Engineering Contradiction:
Improvecoordinate transformation processVSAvoidOCR accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the document image into multiple planar regions based on detected base points and applies separate coordinate transformations to each region. This segmentation allows each transformation to be optimized for its specific region's geometry, maintaining high OCR accuracy across non-coplanar surfaces while keeping individual transformations computationally manageable.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If separate coordinate transformations are determined for each planar region, then OCR accuracy is improved, but computational complexity increases

Engineering Contradiction:
ImproveOCR accuracyVSAvoidcoordinate transformation process
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies different coordinate transformation parameters to different planar regions of the document. Each region receives a transformation optimized for its specific geometric characteristics, allowing high precision OCR for each local area while the overall system manages complexity through region-based processing.

Inventive Principle:
Principle #3Local quality

3Measurement precision

If base points are identified in multiple images, then symbol sequence matching accuracy is improved, but processing time increases

Engineering Contradiction:
Improvesymbol sequence matching accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary identification of base points in multiple images before the main OCR processing. This preliminary action establishes accurate correspondence relationships between images in advance, enabling faster and more accurate symbol sequence matching during the actual recognition process without repeating computationally intensive operations.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS11699294B2Optical character recognition of documents having non-coplanar regions
Publication Date: 2023.07.11 ABBYY DEVELOPMENT INC
  • US11699294B2 patent drawing
  • US11699294B2 patent drawing
  • US11699294B2 patent drawing

AI summary

Systems and methods for performing OCR of an image depicting text symbols and imaging a document having a plurality of planar regions are disclosed. An example method comprises: receiving a first image of a document having a plurality of planar regions and one or more second images of the document; identifying a plurality of coordinate transformations corresponding to each of the planar regions of the first image of the document; identifying, using the plurality of coordinate transformations, a cluster of symbol sequences of the text in the first image and in the one or more second images; and producing a resulting OCR text comprising a median symbol sequence for the cluster of symbol sequences.