Dynamic Window Allocation for Auto White Balance Accuracy

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Solution Overview

Problem

Current white balance adjustment methods, such as the gray world and perfect reflector algorithms, face challenges in accuracy due to color shifts caused by different light sources, especially when dealing with monotonous or chaotic light environments, leading to reduced performance in correcting color distortions.

Innovation Solution

An auto white balance adjusting method and system that dynamically allocates windows within an image based on color information, filters out extreme or chaotic regions, groups color temperatures using a standard curve, and adjusts the white balance with spatially weighted groups to improve accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the gray world algorithm is used for white balance adjustment, then the processing is simple, but the adjustment performance is greatly decreased when the color in the image is relatively monotonous

Engineering Contradiction:
Improvesimplicity of processingVSAvoidwhite balance adjustment performance
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The image is divided into multiple candidate regions (windows) with different sizes and positions. Instead of processing the entire image uniformly, the method segments the image into N candidate windows, then filters and groups these windows based on color temperature characteristics. This segmentation allows the algorithm to focus on representative regions while avoiding monotonous areas, thus improving white balance adjustment performance without excessive computational complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the image are treated differently based on their color temperature characteristics. The method assigns different weights to different candidate windows based on their spatial information and color temperature reliability. Regions with chaotic or extreme light are filtered out or given lower weights, while regions with reliable color temperature information are given higher weights, achieving local optimization of the white balance adjustment.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If the perfect reflection algorithm is used for white balance adjustment, then the adjustment can be performed, but the performance is greatly decreased when the brightest area in the image is not absolutely white

Engineering Contradiction:
Improvewhite balance adjustment capabilityVSAvoidadjustment performance under non-ideal conditions
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The method dynamically selects and weights different candidate windows based on their color temperature characteristics and spatial information. Instead of relying on a fixed assumption about the brightest area being white, the algorithm adaptively identifies reliable regions and adjusts their weights dynamically. This dynamic approach allows the system to handle various lighting conditions effectively, including cases where the brightest area is not absolutely white.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The method changes the parameter of color temperature measurement by using multiple candidate windows with different sizes and positions instead of a single brightest area. By filtering and grouping these windows according to color temperature characteristics and assigning different weights, the algorithm transforms the unreliable single-point measurement into a robust multi-point statistical measurement, improving reliability under non-ideal conditions.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If all regions in the image are used for white balance calculation, then the computation is comprehensive, but chaotic light or extreme light reduces the accuracy of white balance adjustment

Engineering Contradiction:
Improvecomprehensiveness of calculationVSAvoidimpact of chaotic light and extreme light
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The method extracts and filters out candidate windows with chaotic or extreme light characteristics from the set of all candidate windows. By acquiring feature information of each window and filtering based on these features, the algorithm removes harmful regions that would otherwise degrade white balance accuracy. This extraction of useful information while eliminating harmful elements allows comprehensive yet accurate white balance calculation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The method converts the potential harm of chaotic and extreme light into a benefit by using the filtering process to identify and weight reliable regions more heavily. The presence of chaotic light in some regions actually helps the algorithm identify and exclude those regions, thereby benefiting from the contrast between reliable and unreliable areas. The weighting mechanism transforms the heterogeneous mixture of good and bad regions into an optimized set for accurate white balance adjustment.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS12149837B2Auto white balance adjusting method and auto white balance adjusting system by using dynamic window allocations
Publication Date: 2024.11.19 WELTREND SEMICON INC
  • US12149837B2 patent drawing
  • US12149837B2 patent drawing
  • US12149837B2 patent drawing

AI summary

An auto white balance adjusting method includes acquiring an image, allocating N windows inside the image according to color information of the image, filtering out M windows from the N windows for generating N-M windows according to feature information of the N windows, grouping the color temperatures of the N-M windows for generating at least one color temperature group according to a standard color temperature curve, setting a first weighting of the at least one color temperature group according to a correlation between the at least one color temperature group and the standard color temperature curve, setting a second weighting of the at least one color temperature group according to spatial information of the at least one color temperature group of the image, and adjusting a white balance of the image according to color information, the first weighting, and the second weighting.