Image Processing Device Color Balancing
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Solution Overview
Problem
Existing color balancing methods for cameras are inadequate as they require a known color chart, shared field of view, and are inflexible with changing illumination conditions, making them unsuitable for real-time dynamic color balancing in large camera arrays.
Innovation Solution
A novel method that uses a simple linear model to transform the color gamut of each camera based on shared scene pixels, eliminating the need for a color chart and allowing color balancing without a shared field of view, enabling real-time continuous calibration under dynamic environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hardware camera register calibration is used to adjust gain and exposure, then color response can be modified, but the range and precision are inadequate to achieve color consistency
Solution Approach 1:
The patent introduces an intermediary color balancing layer that operates between hardware camera registers and final image output. This software-based intermediary performs precise color space transformations and gamut mappings that extend beyond the limited range of hardware register adjustments, achieving the required precision for color consistency without being constrained by hardware limitations.
Solution Approach 2:
The patent replaces the mechanical/hardware-based register calibration system with a software-based image processing system. By substituting the physical hardware adjustment mechanism with computational color balancing algorithms, the system achieves both the precision and adaptability that hardware alone cannot provide, while maintaining real-time performance through optimized processing.
2Measurement precision
If a known color chart is used for color calibration, then color matching can be performed, but the system lacks flexibility when illumination conditions change
Solution Approach 1:
The patent implements a dynamic color balancing system that continuously adapts to changing illumination conditions. Instead of relying on static color charts, the system uses real-time analysis of shared scene content between cameras to compute and apply color balancing transformations, enabling continuous adaptation to dynamic environmental changes while maintaining color accuracy.
Solution Approach 2:
The system performs self-calibration by automatically analyzing shared scene content between cameras and computing the necessary color balancing transformations without requiring external color charts or manual intervention. The cameras themselves provide the calibration data through their shared field of view, making the system self-sufficient and adaptable to changing conditions.
3Measurement precision
If cameras need overlapping field of view to contain color calibration pattern, then color calibration can be performed, but this is a strict constraint for large camera arrays
Solution Approach 1:
The patent extracts the color calibration function from the physical overlap requirement by using image processing algorithms that can derive color relationships from minimal or no overlapping content. The system extracts color balancing information from shared scene elements that may be partially visible or inferred, eliminating the need for strict geometric overlap constraints between cameras in the array.
Solution Approach 2:
The patent creates a universal color balancing approach that works across diverse camera array configurations regardless of overlapping field of view requirements. The method can handle various scenarios including full overlap, partial overlap, or even non-overlapping cameras by using robust scene analysis and color space transformation techniques that adapt to the available shared content, making the system universally applicable to any camera arrangement.
4Measurement precision
If complex color calibration methods are used to achieve accurate color balancing, then color consistency improves, but processing time increases preventing real-time operation
Solution Approach 1:
The patent transforms the color calibration problem into a set of parameter transformations between color spaces. By representing color balancing as linear or affine transformations with a small number of parameters (gain factors, offset values, white point adjustments), the system achieves accurate color matching through computationally efficient matrix operations rather than complex iterative optimization, enabling real-time processing.
Solution Approach 2:
The patent segments the color balancing process into independent, computationally lightweight stages: color space conversion, white point matching, and gamut transformation. Each stage operates with simplified assumptions and uses pre-computed lookup tables or closed-form solutions, breaking down the complex calibration problem into manageable segments that can be executed rapidly in real-time without sacrificing overall accuracy.
Data Source
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AI summary
An image processing device (10) performing color balancing of a first image (11a) and at least a second image (12a) is provided. The image processing device (10) comprises a color balancing determination unit (20) and a color balancing calculation unit (21). The color balancing determination unit (20) determines a global gain vector (t) comprising at least two gain factors (ân, ân+1) of the first and second images (11a, 12a) by minimizing a cost function based upon reference pixel values of the first and second images (11a, 12a). The first and second image reference pixels depict a shared color scene of the two images. The color balancing calculation unit (21) performs color balancing of the first image (11a) based upon the gain factor (an) of the first image (11a) and to perform a color balancing of the second image (12a) based upon the gain factor (ân+1) of the second image (12a).