Character Image Grouping for More Accurate String Recognition

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Solution Overview

Problem

Existing methods for character recognition in images, such as CRAFT and STAR-Net, suffer from reduced accuracy due to improper clipping of character regions, leading to inefficiencies in recognizing character strings.

Innovation Solution

An information processing device and method that includes probability image acquisition, character region estimation, clustering, and character recognition, where images are classified into a plurality of groups based on estimated positions, and recognition target images are generated to improve accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If character string region is clipped based on probability images, then processing efficiency is improved, but recognition accuracy is reduced

Engineering Contradiction:
Improveprocessing efficiencyVSAvoidrecognition accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent divides the character string region into multiple candidate regions based on different clipping methods (horizontal clipping, vertical clipping, and diagonal clipping). Each clipping method generates separate candidate regions, which are then evaluated to select the most appropriate one for recognition. This segmentation approach allows the system to maintain processing efficiency while improving recognition accuracy by considering multiple potential regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the clipping parameters by applying different clipping methods (horizontal, vertical, diagonal) with varying angles and directions. By adjusting these geometric parameters, the system generates diverse candidate regions that better capture the actual character string boundaries, thereby improving recognition accuracy without sacrificing processing efficiency.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If character string region includes more characters, then clustering accuracy is improved, but recognition complexity increases

Engineering Contradiction:
Improveclustering accuracyVSAvoidrecognition complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the character string region into multiple candidate regions using different clipping methods. Each candidate region contains a subset of characters that can be independently evaluated. This segmentation reduces recognition complexity by breaking down large character groups into manageable subsets while maintaining clustering accuracy through multiple evaluation perspectives.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent generates multiple candidate regions that may include slightly more or fewer characters than the ideal group size. By evaluating multiple partial regions with varying character counts, the system achieves accurate clustering without requiring perfect precision in each individual region, thereby reducing overall recognition complexity.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4064224B1Information processing device, information processing method, and program
Publication Date: 2026.01.07 RAKUTEN GROUP INC
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  • EP4064224B1 patent drawingFigure 2
  • EP4064224B1 patent drawingFigure 3

AI summary

The information processing device acquires a probability image representing a probability of an existence of a character in each of pixels included in a target image including a plurality of characters based on the target image, estimates positions of respective character images included in the target image based on the acquired probability image, classifies the plurality of character images into a plurality of groups based on the estimated positions, acquires a plurality of recognition target images which is generated so as to correspond to the plurality of groups, and includes the plurality of character images respectively belonging to the corresponding groups, and recognizes the plurality of characters from each of the recognition target images.