Document Image Brightness Correction by Affected-Region Segmentation

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Solution Overview

Problem

Existing image processing systems require a long time to perform brightness correction when external light, such as sunlight or illumination, affects only a part of the document installation area, as the entire document image is treated as a correction target.

Innovation Solution

The system performs brightness correction on a specific image area within the document image that meets a predetermined condition, such as an area surrounded by a boundary where brightness switches and an outer peripheral portion on the bright side, using brightness or color differences to identify and correct the affected regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If brightness correction is performed on the entire document image, then the correction covers all areas including those not affected by external light, but the processing time becomes relatively long

Engineering Contradiction:
Improvebrightness correction accuracyVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent divides the document image into multiple regions based on brightness characteristics. A brightness distribution analysis unit separates the image into a first region (with external light influence) and a second region (without external light influence) by comparing brightness values against a threshold. This segmentation allows brightness correction to be applied selectively only to the first region, reducing processing time while maintaining correction accuracy where needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different processing strategies to different regions of the document image. The brightness correction is applied locally only to regions identified as being affected by external light, rather than uniformly across the entire image. This local quality approach optimizes processing efficiency by concentrating computational resources on areas that actually require correction.

Inventive Principle:
Principle #3Local quality

2Reliability

If brightness correction is performed on the entire document image, then comprehensive correction is achieved, but the processing efficiency decreases

Engineering Contradiction:
Improvecorrection completenessVSAvoidprocessing efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements partial action by performing brightness correction only on the portion of the document image that is actually affected by external light. The brightness distribution analysis unit identifies the specific region requiring correction, and the correction unit applies processing only to that region rather than the entire image, thereby improving processing efficiency without compromising the reliability of correction where it is needed.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

By segmenting the document image into regions with and without external light influence, the patent enables selective processing that maintains correction completeness for affected areas while improving overall processing efficiency by excluding unaffected areas from the correction workflow.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4340348B1Information processing apparatus, information processing program, and information processing method
Publication Date: 2025.08.20 FUJIFILM BUSINESS INNOVATION CORP
  • EP4340348B1 patent drawingFigure 1~2
  • EP4340348B1 patent drawingFigure 3~4
  • EP4340348B1 patent drawingFigure 5

AI summary

An information processing apparatus includes a processor configured to perform brightness correction with an image area that satisfies a predetermined condition in a document image of a captured image of an installation area where a document is installed, as a processing target area.