Object Relighting Using Peripheral Luminance to Prevent Brightness Overflow

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Solution Overview

Problem

Existing relighting processing techniques suffer from low accuracy in distance information, leading to unnatural images where brightened regions extend beyond the targeted object region, especially under challenging image capture conditions.

Innovation Solution

An image processing apparatus and method that controls virtual light source parameters based on object distance, luminance, and peripheral luminance to minimize unnaturalness by calculating virtual light reflection components and adjusting brightness levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If relighting processing is performed using distance information, then shadow correction and brightness adjustment are achieved, but the accuracy of distance information is low under challenging image capture conditions, leading to unnatural images where brightened regions extend beyond the targeted object region

Engineering Contradiction:
Improvedistance information accuracyVSAvoidimage naturalness
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces peripheral luminance as an intermediary parameter to indirectly determine object boundaries when direct distance information is unreliable. By analyzing the luminance transition at object peripheries, the system can accurately identify object regions without depending solely on low-accuracy distance data, thus preventing brightened regions from extending beyond object boundaries

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the parameter used for object region determination from relying primarily on distance information to using peripheral luminance characteristics. By detecting luminance transitions and analyzing peripheral pixel values, the system adapts to challenging capture conditions where distance information is unreliable, maintaining image naturalness through alternative parameter-based object boundary detection

Inventive Principle:
Principle #35Parameter changes

2Illumination intensity

If virtual light source parameters are controlled based on distance information, then brightness correction is applied to objects, but low accuracy distance information causes brightness corrections to extend beyond the intended object region

Engineering Contradiction:
Improvevirtual light brightnessVSAvoidbrightness correction precision
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by using peripheral luminance to define precise local object boundaries before applying brightness correction. By analyzing luminance transitions at each peripheral region, the system ensures that virtual light parameters are applied only to appropriate local areas, preventing overflow into background regions while maintaining accurate brightness correction within object boundaries

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements feedback by using detected peripheral luminance characteristics to adjust and refine the object region mask before applying relighting. The system continuously refines the boundary definition based on luminance transition feedback, ensuring that brightness corrections are precisely confined to object regions even when initial distance information is inaccurate

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3832592B1Correction of brightness of an object in an image
Publication Date: 2025.08.13 CANON KK
  • EP3832592B1 patent drawingFigure 1
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AI summary

An image processing apparatus comprises a detection unit (113) configured to detect region information of an object in an image, an acquisition unit (105) configured to detect a predetermined object region that is a part of the object from the region information of the object, and to acquire luminance information of a periphery of the predetermined object region, and a relighting unit (114) configured to perform processing for correcting brightness of the object in the image by adding an effect of virtual light. The relighting unit corrects the brightness of the object including the predetermined object region in accordance with luminance of the periphery of the predetermined object region.