Digital Camera Exposure Control Using Segmented Photometry
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Solution Overview
Problem
Digital photographing apparatuses often fail to accurately adjust exposure and white balance, resulting in captured images that differ from the subject's perceived colors and luminance.
Innovation Solution
A digital photographing apparatus is equipped with a display unit, position setting unit, area setting unit, photometry unit, exposure value determination unit, and colorimetric unit, allowing for precise adjustment of exposure and white balance by measuring luminance and color of specific areas, using various photometric and colorimetric references to set optimal exposure and color-temperature settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional exposure and white balance adjustment methods are used, then the device complexity is reduced, but the measurement precision and image quality deteriorate
Solution Approach 1:
The photometry system is segmented into multiple independent photometry units, each responsible for measuring luminance in specific luminance ranges (highlight, average, shadow areas). This segmentation allows precise measurement of different luminance regions without requiring a single complex photometry system, as each unit can be optimized for its specific measurement range.
Solution Approach 2:
The patent introduces multiple photometric reference dimensions (first photometric reference for highlight areas, second photometric reference for average areas, third photometric reference for shadow areas) instead of using a single photometric reference. This multi-dimensional approach enables precise exposure measurement across different luminance ranges by selecting appropriate references based on the specific measurement needs.
2Measurement precision
If multiple photometric references are used to improve exposure accuracy, then the measurement precision improves, but the ease of operation deteriorates
Solution Approach 1:
The exposure value determination unit automatically selects the appropriate photometric reference (first, second, or third) based on the luminance characteristics of the measured area without requiring manual intervention. The system self-services by intelligently determining which photometric reference to apply, eliminating the need for users to manually configure complex photometric settings while maintaining high measurement precision.
Solution Approach 2:
The system dynamically changes photometric parameters by selecting different photometric references based on the luminance range of the measured area. When measuring highlight areas, it applies the first photometric reference; for average areas, the second reference; and for shadow areas, the third reference. This automatic parameter adaptation simplifies operation while achieving precise exposure measurement across varying luminance conditions.
3Measurement precision
If conventional colorimetric measurement is used, then the device complexity is minimized, but the color accuracy and white balance quality deteriorate
Solution Approach 1:
The colorimetric measurement system is segmented to focus on measuring colors in specific luminance ranges (particularly mid-tone and shadow areas) rather than attempting to measure all colors uniformly across the entire image. This segmentation allows the colorimetric unit to concentrate its measurement efforts on areas that are most critical for accurate white balance determination, improving color measurement precision without requiring a fully complex colorimetric system.
Solution Approach 2:
The patent applies different colorimetric measurement strategies to different luminance regions of the image. The colorimetric unit measures colors in specific areas (such as shadow and mid-tone regions) with higher precision, while relying on other methods for other areas. This local quality approach ensures accurate color measurement where it matters most for white balance without uniformly increasing system complexity across all measurement regions.
4Manufacturing precision
If precise photometry and colorimetry are performed on multiple areas, then the manufacturing precision of image quality improves, but the loss of time increases
Solution Approach 1:
The patent performs preliminary photometry operations by measuring luminance in multiple areas and determining highlight, average, and shadow area luminance values before final exposure calculation. This preliminary action allows the exposure value determination unit to have all necessary luminance data ready, enabling faster final exposure determination without sacrificing measurement precision. The colorimetric measurements are also performed in advance on selected areas, preparing color data for subsequent white balance adjustment.
Solution Approach 2:
Instead of performing exhaustive photometry and colorimetry on every area of the image, the system performs measurements on strategically selected areas (highlight areas, average areas, shadow areas, and specific colorimetric regions). This partial action approach captures sufficient information for accurate exposure and white balance determination without the time cost of measuring every pixel, achieving a balance between image quality precision and processing time.
Data Source
AI summary
A digital photographing apparatus including: a display unit for displaying a captured image; a position setting unit for setting a position on the display unit; an area setting unit for setting an area based on the position set by the position setting unit; a photometry unit for measuring luminance of the set area; an exposure value determination unit for determining an exposure value based on a photometric reference and a result of the measuring performed by the photometry unit. The digital photographing apparatus may capture a high quality image by properly adjusting exposure and white balance.