Dual Exposure Image Sensor Rows for Wide Dynamic Range
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Solution Overview
Problem
Existing image sensors face challenges in increasing dynamic range due to difficulties in selecting optimal exposure durations, leading to either pixel saturation or loss of detail, with conventional methods being expensive or susceptible to motion artifacts.
Innovation Solution
A method involving dual exposure techniques where alternating rows of an image sensor array are exposed for different durations, with pixel values being scaled or interpolated based on thresholds to create a wide dynamic range image without requiring multiple sensors or sequential image acquisitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single exposure duration is used for the entire image sensor array, then the device complexity is low, but the dynamic range is limited due to pixel saturation or loss of detail
Solution Approach 1:
The image sensor array is divided into multiple rows, where alternating rows are exposed for different durations (first exposure duration for odd rows, second exposure duration for even rows). This segmentation allows different portions of the sensor to capture different exposure levels simultaneously, expanding the overall dynamic range without requiring multiple separate sensors or sequential acquisitions.
Solution Approach 2:
Different rows of the image sensor array are assigned different exposure durations based on local image quality requirements. Rows capturing brighter regions use shorter exposure durations to prevent saturation, while rows capturing darker regions use longer exposure durations to preserve detail, optimizing image quality locally across the entire array.
2Measurement precision
If multiple image sensors are used to capture different exposure durations, then the dynamic range increases, but the device complexity and cost increase significantly
Solution Approach 1:
Instead of using multiple separate image sensors, the patent segments a single image sensor array into multiple rows with different exposure characteristics. This approach achieves the dynamic range benefits of multiple sensors while using only one physical sensor device, thereby reducing complexity and cost.
Solution Approach 2:
A single image sensor array performs multiple functions by having different rows operate with different exposure durations simultaneously. This multi-functionality allows one sensor to replace what would traditionally require multiple sensors, reducing system complexity while maintaining expanded dynamic range capabilities.
3Device complexity
If sequential image acquisitions are used to obtain multiple exposures, then the device complexity is reduced, but motion artifacts appear in the resulting image
Solution Approach 1:
The image sensor array is segmented into rows that simultaneously capture different exposure durations during a single acquisition event. This eliminates the temporal separation inherent in sequential acquisitions, thereby preventing motion artifacts while maintaining the benefits of multiple exposure levels.
Solution Approach 2:
Alternating rows of the image sensor array are exposed in a periodic alternating pattern (odd rows for first exposure, even rows for second exposure) during the same acquisition window. This periodic structure allows simultaneous capture of multiple exposure levels without temporal displacement, eliminating motion artifacts.
4Measurement precision
If a longer exposure duration is used, then detail in dark regions is improved, but pixels in bright regions become saturated
Solution Approach 1:
The image sensor array is divided into rows with different exposure durations, allowing dark regions to be captured with longer exposure (preserving detail) while bright regions are captured with shorter exposure (preventing saturation). This segmentation resolves the trade-off between capturing dark and bright details simultaneously.
Solution Approach 2:
Different rows are assigned different exposure durations based on the local brightness characteristics of the scene. Rows capturing brighter regions use shorter exposure to avoid saturation, while rows capturing darker regions use longer exposure to preserve detail, optimizing image quality for each local region.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances image quality by reducing signal-to-noise ratio and preventing saturation, while avoiding the need for multiple sensors and minimizing motion artifacts, thus improving the dynamic range of image sensors effectively.
Implementation Method 1
a first plurality of rows of photodetectors in the image sensor array are exposed for a first duration to a first image
Data Source
AI summary
A method of capturing an image of a scene using an image capture device having an array of pixels arranged into a plurality of rows includes, for a first duration, capturing a first portion of the scene with a first plurality of the rows and, for a second duration that is longer than the first duration, capturing a second portion of the scene with a second plurality of the rows. If a pixel value is below a first threshold, an interpolated pixel value is used. If the pixel value is above a second predetermined threshold, a different interpolated pixel value is used.