Exposure Control Circuitry Using Distortion-Weighted Pixel Counting
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Solution Overview
Problem
Existing imaging systems with wide-angle lenses face challenges in accurately controlling exposure due to image distortion, leading to delayed and inaccurate pixel counting, which affects the quality of images and feedback control in devices like endoscopes and digital cameras.
Innovation Solution
The implementation of an exposure control circuitry that counts pixels in the distorted image, incorporating area-stretch weights to account for the effects of unwarping, allowing for real-time exposure control and improved image quality by using distortion models to weight pixel contributions based on their distortion characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel counting is performed on the distorted image, then exposure control speed is improved, but exposure accuracy deteriorates
Solution Approach 1:
The patent introduces an intermediary computational step between distorted image acquisition and exposure control decision-making. Instead of directly counting pixels in the distorted image or waiting for undistorted image processing, the system applies a pre-calculated distortion model to compute weighted pixel contributions. This intermediary calculation accounts for the non-linear mapping between distorted and undistorted spaces, providing accurate exposure metrics without the time delay of full undistorted image processing.
Solution Approach 2:
The system performs preliminary action by pre-calculating and storing distortion models that characterize the relationship between distorted and undistorted image spaces. These pre-computed models enable real-time exposure control calculations to be performed quickly using simple weighted sums, rather than performing complex undistortion operations during the exposure control loop. The preliminary preparation of distortion characteristics allows fast, accurate exposure decisions.
2Measurement precision
If pixel counting is performed on the undistorted image, then exposure accuracy is improved, but exposure control delay increases
Solution Approach 1:
The patent creates a computational copy of the undistorted image metrics directly from the distorted image data using a distortion model. Instead of physically transforming the distorted image into an undistorted image (which is time-consuming), the system computes what the pixel distribution would be in the undistorted space by applying weighting factors derived from the distortion model. This copying approach provides accurate undistorted-image-based exposure metrics without the time penalty of actual image transformation.
Solution Approach 2:
The system changes the parameter representation from actual pixel values in distorted space to weighted pixel values that represent undistorted space. By transforming the exposure calculation from a spatial operation (requiring image undistortion) to a parameter operation (applying pre-computed weights to existing pixel values), the system achieves undistorted-image accuracy with distorted-image speed. The parameter change enables exposure control to operate in the faster distorted image domain while maintaining undistorted image fidelity.
Data Source
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AI summary
Improved exposure control processes, devices, and systems are provided for wide angle lens imaging systems that suffer from image distortion. The exposure control uses a model of the wide angle lens distortion that estimates the weights that respective pixels of the image would have when producing an undistorted version of the image signal, and then scales pixel intensity values by the respective weights to produce weighted pixel values. The weighted pixel values are provided to an exposure control pixel counting process to produce one or more exposure feedback control signals, which control exposure features of the imaging system.