Handwritten Text Recognition with Independent OCR Error Prediction

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Solution Overview

Problem

Existing optical character recognition (OCR) systems face challenges in accurately recognizing handwritten text due to variations in handwriting styles, leading to high error rates and a lack of confidence in recognition results.

Innovation Solution

A neural network architecture is employed that includes a convolutional neural network (CNN) for feature extraction, followed by a recurrent neural network (RNN) with Long Short-Term Memory (LSTM) layers for sequence modeling, and a Connectionist Temporal Classification (CTC) layer for transcription, combined with an independent error prediction branch to estimate the error level of the recognition output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional OCR techniques are used for handwritten text recognition, then the system is simple to implement, but the recognition accuracy is low due to handwriting style variations

Engineering Contradiction:
Improverecognition accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system segments the handwritten text recognition task into multiple independent neural network components: a CNN for feature extraction, an RNN for sequence modeling, and a CTC layer for transcription. This segmentation allows each component to specialize in a specific aspect of the recognition process, improving overall accuracy while maintaining manageable system complexity through modular architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system employs a composite neural network architecture that combines different types of neural networks (CNN and RNN) with different functions. The CNN extracts spatial features from image patches, while the RNN models temporal dependencies in the character sequence. This composite approach leverages the strengths of each network type to achieve high recognition accuracy for handwritten text.

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If a complex neural network architecture is used to improve recognition accuracy, then the measurement precision improves, but the computational resources and time required increase

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

Solution Approach 1:

The system performs preliminary feature extraction using the CNN before passing data to the RNN for sequence modeling. This preliminary action of extracting relevant features from image patches reduces the dimensionality and complexity of the data that the RNN must process, thereby reducing computational time while maintaining recognition accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system processes the handwritten text in partial segments (image patches) rather than attempting to process the entire image at once. The CTC layer processes these partial sequences independently and combines them, which reduces the computational burden compared to processing the full sequence in one pass, thereby reducing processing time while maintaining accuracy.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If traditional OCR systems are used, then the system is easy to operate, but the reliability of recognition results is low due to high error rates

Engineering Contradiction:
Improvereliability of recognition resultsVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system incorporates a confidence estimation mechanism that provides feedback about the reliability of each recognition result. The neural network outputs confidence scores that indicate the likelihood of correct recognition, allowing the system to identify and flag uncertain predictions. This feedback mechanism improves reliability by enabling post-processing validation or human review of low-confidence results.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts its processing based on the complexity of the handwritten text. The neural network architecture adapts to different handwriting styles, script types, and text qualities by learning from training data. This dynamic adaptation capability allows the system to maintain high reliability across diverse inputs without requiring manual configuration or simplification.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3685312B1Method and system for image content recognition
Publication Date: 2025.07.23 RAMOT AT TEL AVIV UNIVERSITY LTD
  • EP3685312B1 patent drawingFigure 1
  • EP3685312B1 patent drawingFigure 2A~2B
  • EP3685312B1 patent drawingFigure 3

AI summary

A method of recognizing image content, comprises applying to the image a neural network which comprises an input layer for receiving the image, a plurality of hidden layers for processing the image, and an output layer for generating output pertaining to an estimated image content based on outputs of the hidden layers. The method further comprises applying to an output of at least one of the hidden layers a neural network branch, which is independent of the neural network and which has an output layer for generating output pertaining to an estimated error level of the estimate. A combined output indicative of the estimated image content and the estimated error level is generated.