Omnidirectional Camera Exposure Control Using Overlap Exclusion
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Solution Overview
Problem
Conventional imaging devices, particularly omnidirectional cameras with fisheye lenses, face challenges in accurately controlling exposure due to high brightness environments and overlapping image areas, leading to inconsistencies in frame exposure during video capture.
Innovation Solution
A control system that calculates exposure evaluation values for each fisheye lens image by excluding pixel values from overlapping areas, allowing for precise adjustment of shutter speed and ISO sensitivity to achieve correct exposure, thereby stabilizing exposure control across frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exposure control is performed using all pixel values including overlapping areas, then calculation is simpler, but exposure control becomes unstable and inaccurate
Solution Approach 1:
The patent segments the image data from multiple fisheye lenses by identifying and separating overlapping areas from non-overlapping areas. The exposure evaluation is then performed separately for each region, with the overlapping regions being excluded from the brightness calculation. This segmentation approach resolves the contradiction by maintaining measurement precision through selective data usage while avoiding the complexity of handling conflicting exposure information from overlapping regions.
Solution Approach 2:
The patent applies different quality requirements to different regions of the image. Specifically, it recognizes that overlapping areas have different characteristics (potential exposure inconsistencies) compared to non-overlapping areas. By excluding overlapping areas from the exposure evaluation calculation, the system applies a local quality filter that prioritizes stable exposure control in the majority of the image while accepting that the overlapping boundary regions will be excluded from the control decision.
2Illumination intensity
If shutter speed is increased for high brightness environments, then exposure control range is extended, but shutter speed resolution becomes coarser
Solution Approach 1:
The patent performs preliminary evaluation of exposure conditions by calculating brightness values from image data before finalizing the exposure control settings. By pre-assessing the brightness level and excluding overlapping areas from this evaluation, the system can determine the appropriate shutter speed setting in advance, ensuring both adequate brightness handling and sufficient resolution in the selected shutter speed range.
3Area of stationary object
If exposure control is performed using multiple imaging elements, then coverage is improved, but stability deteriorates in overlapping areas
Solution Approach 1:
The patent extracts and excludes the problematic overlapping area data from the exposure evaluation calculation. By taking out the overlapping regions from the set of pixels used for brightness evaluation, the system maintains the benefit of using multiple imaging elements for comprehensive coverage while eliminating the source of instability caused by overlapping area inconsistencies.
Data Source
AI summary
A control system controls an imaging device to generate an omnidirectional image based on a first image obtained using a first fisheye lens and a second image obtained using a second fisheye lens. The control system includes an evaluation value calculating unit configured to: calculate brightness values of the first and second images based on pixel values of pixels constituting the first and second images, and calculate, based on the brightness values, first and second exposure evaluation values for evaluating exposure of first and second imaging elements corresponding to the first and second fisheye lenses. The evaluation value calculating unit configured to do not use pixel values of pixels constituting an overlapping area in which there is overlapping of shooting ranges of the first and second images, during calculation of the brightness values of the first and second images.