Auto-Exposed HDR Imaging System with Dynamic Exposure Control
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Solution Overview
Problem
Conventional high-dynamic-range (HDR) imaging systems often capture images with inappropriate exposure times, leading to insufficient dynamic range capture in combined images, particularly in scenes with high contrast, resulting in loss of highlight and shadow detail.
Innovation Solution
An imaging system that employs an exposure determination engine to automatically determine and adjust long and short exposure times based on scene dynamics, using sub-engines for generating auto-exposure statistics, measurement, tracking, and ratio control to optimize exposure settings for image sensors, allowing for flexible HDR imaging across varying dynamic ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional image systems use fixed exposure times, then the imaging process is simple, but the dynamic range capture is insufficient in high-contrast scenes
Solution Approach 1:
The system dynamically adjusts exposure times for different pixel groups based on scene conditions. The exposure determination engine continuously monitors scene dynamics and modifies long and short exposure times accordingly, transforming the static exposure system into a dynamic one that adapts to varying scene requirements.
Solution Approach 2:
The system implements feedback mechanisms where the exposure determination engine analyzes captured images and scene statistics, then adjusts subsequent exposure settings based on this analysis. The exposure tracking engine monitors exposure levels and provides feedback to optimize the exposure ratio between long and short exposure images.
2Adaptability or versatility
If manual exposure adjustment is used, then exposure control is simple, but the system cannot adapt to varying scene dynamics automatically
Solution Approach 1:
The exposure determination engine autonomously determines optimal exposure settings without requiring manual intervention. The system self-adjusts exposure times by analyzing scene statistics, tracking exposure levels, and controlling the exposure ratio automatically, enabling the device to serve itself in adapting to different scene conditions.
Solution Approach 2:
The system performs preliminary analysis of scene dynamics and exposure requirements before capturing the final HDR image. The exposure determination engine pre-calculates optimal long and short exposure times based on initial scene assessment, ensuring proper exposure settings are established before the actual imaging sequence.
3Reliability
If single exposure time is used, then the imaging process is fast, but highlight and shadow details cannot be retained simultaneously
Solution Approach 1:
The system segments the image capture process into multiple exposures with different time durations. By dividing the imaging task into short exposure (for highlights) and long exposure (for shadows) components, the system captures complementary detail information that would be lost in a single exposure, then combines them in the HDR processing stage.
Solution Approach 2:
The system employs periodic capture of short and long exposure images in sequence. This periodic alternating exposure approach allows the system to efficiently gather both highlight and shadow information through repeated cycles of dual exposure capture, maintaining imaging speed while ensuring detail retention across the dynamic range.
Data Source
AI summary
Electronic devices may have camera modules that include an image sensor and processing circuitry. The image sensor may capture an image from a scene. The processing circuitry may extract image statistics and exposure levels from the image. The processing circuitry may use the image statistics and the exposure levels to generate a first exposure time, a second exposure time, and gain settings for the image sensor. The image sensor may capture additional images from the scene having long-exposure image pixel values that are captured using the first exposure time and short-exposure image pixel values that are captured using the second exposure time. The processing circuitry may generate a long-exposure image and a short-exposure image from the second image. The processing circuitry may generate auto-exposed high-dynamic-range images of the scene using the long-exposure image and the short-exposure image.