Illuminant Estimation Using Pixel Subset and Chromaticity Area
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Solution Overview
Problem
Current image processing systems in cameras face high computational complexity when determining the actual illuminant of a scene, which requires substantial processing resources and can be inefficient.
Innovation Solution
The system reduces computational complexity by comparing only a subset of color values from an image frame with pre-stored data representing how colors appear under different illuminants, using a subset of pixels and forming areas in chromaticity space to minimize unnecessary rotations and calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the system compares all color values in the image frame with pre-stored reference color data to determine the actual illuminant, then the accuracy of illuminant determination is improved, but the computational complexity and processing resource requirements increase substantially
Solution Approach 1:
The patent divides the image frame into multiple regions of interest (ROIs) and selectively processes only the color values within these regions. By segmenting the image into specific areas such as skin tone regions, object regions, and background regions, the system reduces the total number of color values that need to be compared against reference data, thereby lowering computational complexity while maintaining accurate illuminant determination in the most critical areas.
Solution Approach 2:
The patent applies different processing strategies to different regions of the image based on their local characteristics. Regions with specific color properties (such as skin tones or known object colors) are processed with higher detail, while regions with less diagnostic value are processed more lightly. This local quality approach ensures that computational resources are concentrated on areas that provide the most information about the illuminant, improving accuracy where needed without unnecessarily increasing overall computational complexity.
2Reliability
If the system processes all pixels in the image frame to determine illuminant characteristics, then the reliability of white balance correction is improved, but the processing time and energy consumption increase
Solution Approach 1:
The patent applies partial action by processing only a subset of pixels rather than all pixels in the image frame. The system identifies and processes pixels in specific regions that are most indicative of the illuminant characteristics, such as regions with skin tones or known reflectance properties. This partial processing approach maintains sufficient reliability for accurate white balance correction while significantly reducing processing time and energy consumption compared to processing every pixel.
Solution Approach 2:
The patent performs preliminary actions by pre-identifying regions of interest and pre-computing reference color data for different illuminants. The system prepares lookup tables and reference databases before actual image processing occurs, enabling rapid comparison and determination of illuminant characteristics during image capture. This preliminary preparation reduces the time required for actual illuminant determination while maintaining high reliability in white balance correction.
3Adaptability or versatility
If the system uses a comprehensive set of reference color data for all possible illuminants, then the adaptability to different lighting conditions is improved, but the device complexity and storage requirements increase
Solution Approach 1:
The patent segments the reference color data into organized categories corresponding to different illuminant types (e.g., daylight, incandescent, fluorescent, shadow). By structuring the reference database in this segmented manner and only loading or processing relevant reference data for the current lighting conditions, the system maintains adaptability to various illuminants while reducing the effective storage and processing requirements at any given time.
Solution Approach 2:
The patent implements dynamic adaptation by adjusting the set of reference color data used based on the detected characteristics of the image and estimated illuminant. The system dynamically selects which reference data to process and compare based on the current imaging conditions, allowing the device to adapt to different lighting scenarios without requiring all possible reference data to be actively processed simultaneously, thus reducing effective device complexity and storage usage.
Data Source
AI summary
In an embodiment, computational complexity of estimating the actual illuminant of a scene is reduced by examining only a subset of the pixel values generated for a received image frame. In another embodiment, number of rotations of color values is minimized by selecting an area which contains the color cue values of a color in an original/unrotated coordinate space and has boundaries which parallel the axis of the original coordinate space, and rotating a color value only if the color value is within the selected area. In another embodiment, such an area is used in conjunction with a histogram-based approach to determine the actual illuminant.