Luminance Mapping for Image Brightening Without Color Distortion

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Solution Overview

Problem

Current image brightening processes in electronic devices often distort colors, especially in brighter areas, leading to loss of details and blurriness, as they enhance RGB values uniformly, which can cause colors to transition towards grey and lose focus on critical areas like faces.

Innovation Solution

A method of image processing that separates images into chrominance-luminance modes, traverses luminance components, generates a luminance mapping relationship between standard and original distributions, and adjusts luminance components based on pixel ratios to maintain color integrity and enhance brightness without distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If RGB values of each pixel are enhanced uniformly to brighten the image, then the brightness of darker areas is improved, but colors transition towards grey and details in brighter areas are distorted and lost

Engineering Contradiction:
Improveimage brightnessVSAvoidcolor accuracy
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The image processing method segments the image into multiple luminance regions (first luminance region for darker areas, second luminance region for brighter areas) based on luminance thresholds. Different processing strategies are applied to each region: the first region undergoes stronger brightening while the second region undergoes milder adjustment, thereby preventing color distortion and detail loss in originally brighter areas while still improving overall image brightness

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality adjustment by using region-specific mapping relationships (first luminance mapping relationship for darker areas, second luminance mapping relationship for brighter areas) instead of uniform global adjustment. This allows each region to receive tailored luminance adjustment that preserves its local color characteristics and detail quality while achieving the desired brightness improvement

Inventive Principle:
Principle #3Local quality

2Measurement precision

If RGB values are enhanced to improve image definition, then darker areas become brighter, but colors become distorted and blurry in brighter regions

Engineering Contradiction:
Improveimage definitionVSAvoiddetail loss
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The image is segmented into luminance regions with different characteristics. The first luminance region (darker areas) receives enhanced processing to improve definition, while the second luminance region (brighter areas) receives conservative processing to preserve existing details, thereby achieving overall definition improvement without detail loss

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent dynamically adjusts processing parameters (luminance mapping relationships) based on the input image's luminance distribution characteristics. By analyzing the histogram and determining appropriate thresholds, the system adapts the strength of luminance adjustment for different regions, ensuring that definition enhancement does not lead to information loss

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If uniform brightening is applied to the entire image, then overall brightness is improved, but critical areas such as faces may lose focus and become blurry

Engineering Contradiction:
Improveoverall brightnessVSAvoidfocus quality
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent identifies and protects critical regions by applying milder luminance adjustment (second mapping relationship) to the second luminance region that contains important details like faces. This local quality preservation ensures that while overall brightness is improved, critical areas maintain their focus quality and do not become blurry

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3614335B1Method for image processing and electronic device
Publication Date: 2022.07.20 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD
  • EP3614335B1 patent drawingFigure 1
  • EP3614335B1 patent drawingFigure 2a~2b
  • EP3614335B1 patent drawingFigure 3

AI summary

A method for image processing and an electronic device are disclosed. The method includes obtaining (101) an image in a chrominance-luminance separated color mode; traversing (102) luminance components of all pixels in the image to determine a number of pixels corresponding to the respective luminance component; generating (103) an original luminance distribution of the image based on the luminance components and the number of the pixels corresponding to the respective luminance component; generating (104) a luminance mapping relationship between a preset standard luminance distribution and the original luminance distribution; and adjusting (105) the luminance components of the pixels in the image based on the luminance mapping relationship to obtain a processed image.