Image White Balance Using Illumination Basis Estimation
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Solution Overview
Problem
Existing white balance techniques, such as the Gray World algorithm, fail to accurately adjust image colors under non-uniform lighting conditions, leading to incorrect color representation.
Innovation Solution
An image acquisition apparatus that includes multiple sensors to gather environmental data and estimate illumination information using a selected basis set, performing color conversion based on the estimated illumination without relying on the Gray World assumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the Gray World assumption is used for white balance, then the method is simple to implement, but it fails when the assumption constraints are not satisfied
Solution Approach 1:
The patent changes the fundamental parameter of white balance from assuming uniform channel averages (Gray World) to using spectral decomposition with environmental context. By incorporating sensors that detect illumination spectrum and using basis functions to model light sources, the system adapts to varying illumination conditions rather than relying on fixed assumptions, resolving the contradiction between simplicity and reliability.
Solution Approach 2:
The patent introduces environmental sensors and spectral analysis as intermediary components between the image sensor and white balance processing. These intermediaries provide actual illumination information rather than relying on image statistics alone, enabling accurate color correction even when Gray World assumptions fail.
2Measurement precision
If environmental sensors and spectral decomposition are used, then illumination estimation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the white balance problem into distinct functional modules: environmental sensing, spectral decomposition, basis function selection, and color correction. This segmentation allows each component to be optimized independently and facilitates implementation using existing sensor technologies and processing algorithms, managing complexity while maintaining accuracy.
Solution Approach 2:
The patent employs basis functions that can represent multiple types of illumination sources (natural light, artificial lighting, fluorescent, LED) within a unified mathematical framework. This universal approach allows the system to handle diverse lighting conditions with a single algorithmic structure, reducing complexity compared to implementing separate solutions for each light source type.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurately adjusts image colors across varying lighting conditions, ensuring precise color representation by directly estimating the illumination spectrum and selecting appropriate basis sets for improved white balance.
Implementation Method 1
An image sensor is a device that receives light incident from an object, and photoelectrically converts the received light to generate an electrical signal.
Implementation Method 2
The image sensor uses a color filter, which consists of an array of filter elements that selectively transmit red light, green light, and blue light for color expression
Implementation Method 3
a second pixel array having a spectral filter in which a filter group including a plurality of unit filters having different transmission wavelength bands is repeatedly provided
Data Source
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AI summary
Provided is an image acquisition apparatus including an image sensor configured to obtain an image, and a processor configured to obtain a basis based on a surrounding environment of the image acquisition apparatus, estimate illumination information based on the obtained basis, and perform color conversion on the image based on the estimated illumination information.