Image Processing Apparatus Illumination Color Adjustment
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Solution Overview
Problem
Existing image processing techniques struggle to accurately adjust color shades in images captured under diverse lighting conditions, particularly when there is a significant difference between dark and light portions, leading to poor visibility and mismatch between the photographed image and the actual scene.
Innovation Solution
An image processing apparatus that calculates illumination light intensity and source color using smoothed pixel values, employing Gaussian functions for smoothing and retinex principle-based separation of illumination and reflectance components, allowing for more accurate adjustment of illumination light source color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If auto-white balancing technique is used to adjust color shades, then color accuracy is improved, but visibility in images with large brightness differences deteriorates
Solution Approach 1:
The patent segments the image processing into two distinct components: illumination light component extraction and reflectance component enhancement. By separating these functions, the system can independently optimize color accuracy through illumination estimation while maintaining visibility through reflectance enhancement, resolving the contradiction between color accuracy and visibility in high-contrast scenes
Solution Approach 2:
The patent changes the processing parameters by introducing multiple smoothing degrees (different sigma values in Gaussian filtering) to extract illumination light components at various scales. This multi-scale approach allows the system to adapt to different lighting conditions and brightness ranges, improving both color accuracy and visibility simultaneously by selecting appropriate smoothing parameters for different scene conditions
2Reliability
If retinex principle is used to improve visibility by adjusting dynamic range, then visibility is improved, but color accuracy deteriorates
Solution Approach 1:
The patent explicitly segments the image into illumination light component and reflectance component using the retinex principle. By separating these components, the system can enhance visibility through dynamic range adjustment of the reflectance component while preserving color accuracy through proper estimation and processing of the illumination light component, thus resolving the contradiction between visibility improvement and color accuracy maintenance
3Productivity
If simple smoothing is used for illumination estimation, then processing speed is improved, but measurement precision of illumination light component deteriorates
Solution Approach 1:
The patent applies partial smoothing actions by using multiple smoothing degrees rather than a single aggressive smoothing operation. This allows the system to achieve adequate illumination estimation accuracy through a combination of mild smoothing operations at different scales, avoiding the need for excessive single-step smoothing that would lose detail while maintaining processing efficiency through the structured multi-scale approach
Data Source
AI summary
An image processing apparatus includes an illumination light intensity calculating unit that determines, from a brightness value based on a pixel value of each pixel forming an original image, an illumination light intensity image having as a pixel value an illumination light component of the original image, using at least one smoothed image having the brightness value that is smoothed using at least a smoothing degree, and a light source color calculating unit that determines an illumination light source color as a light source color of illumination light in accordance with the original image and the illumination light intensity image.