Exposure Control Mixing Subject Background Regions
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Solution Overview
Problem
Existing imaging apparatuses perform exposure control based on luminance differences between subject and background regions without considering camera settings or environmental factors, leading to unstable exposure, especially with flash light emission.
Innovation Solution
A control apparatus that calculates exposure control amounts by extracting subject and background regions from an image, determining contribution ratios based on photometric values, and adjusts these ratios considering imaging-related information such as environment, settings, and user preferences to ensure stable exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If exposure control is performed based solely on luminance difference between subject and background regions, then the exposure control process is simple, but the exposure stability deteriorates due to unintended overexposure or underexposure in complex lighting conditions
Solution Approach 1:
The patent implements dynamic adjustment of contribution ratios for subject region and background region exposure control amounts based on imaging conditions. The exposure control amount calculating section dynamically determines the weight of each region's exposure control amount by comparing luminance values and considering flash emission status, allowing the system to adapt to varying lighting conditions rather than using fixed weights
Solution Approach 2:
The patent changes the parameter of contribution ratios based on imaging-related information including flash emission status, subject region luminance, and background region luminance. When flash is emitted and subject region is brighter than background, the background region's contribution ratio is increased to prevent overexposure. This parameter adaptation resolves the contradiction by maintaining simple regional division while achieving stable exposure through conditional parameter adjustment
2Reliability
If the contribution ratio of background region exposure control amount is increased to prevent overexposure, then exposure stability improves, but the subject region may become underexposed
Solution Approach 1:
The system dynamically adjusts contribution ratios based on real-time comparison of subject and background luminance values. When the subject region is brighter than the background region and flash is emitted, the background region's contribution ratio is increased to prevent overexposure. When the subject region is darker or flash is not emitted, the subject region's contribution ratio is prioritized to ensure proper subject exposure
Solution Approach 2:
The patent implements conditional parameter changes where the contribution ratios are modified based on specific conditions: flash emission status and relative luminance comparison between subject and background regions. This ensures that exposure precision is maintained for the subject region while achieving overall exposure stability through context-dependent parameter adjustment
3Manufacturing precision
If exposure control considers multiple imaging-related information including environment, settings, and user preferences, then exposure accuracy improves, but the control system complexity increases
Solution Approach 1:
The patent segments the exposure control system into distinct functional sections: image extracting section for separating subject and background regions, region-specific exposure control amount calculating section for computing exposure values for each region, and exposure control amount calculating section for determining final exposure by combining regional values with imaging-related information. This segmentation manages complexity by organizing the control system into modular, specialized components
Solution Approach 2:
The patent introduces an intermediary exposure control amount calculating section that mediates between the region-specific exposure control amounts and the final exposure decision. This intermediary processes multiple imaging-related information (flash emission status, luminance comparisons, user preferences) and translates them into appropriate contribution ratios, simplifying the overall control logic while maintaining high exposure accuracy
Data Source
AI summary
A region extracting section 31 extracts an image of a subject region and an image of a background region from a picked up image. A region-specific exposure control amount calculating section 33 calculates a subject region exposure control amount based on the image of the subject region and a background region exposure control amount based on the image of the background region. An exposure control amount calculating section 34 sets a contribution ratio of the subject region exposure control amount and a contribution ratio of the background region exposure control amount, and calculates an exposure control amount for use in exposure adjustment by mixing the subject region exposure control amount and the background region exposure control amount at a mixing ratio based on the set contribution ratios. A control section 55 controls a shutter speed, an aperture value, and other settings based on the exposure control amount calculated by the exposure control amount calculating section 34. Thus, regardless of whether or not flash light emission is to be performed, stable exposure is obtained with natural, balanced brightness ensured in the picked up image.