CMOS Image Sensor Dynamic Range via Row Segmentation
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Solution Overview
Problem
Current methods for increasing the dynamic range of captured images using CMOS image sensors either require multiple image sensors, which are expensive, or sequential acquisitions that are susceptible to motion artifacts, and existing dual exposure techniques do not fully address the need for improved image quality.
Innovation Solution
A method that involves reading pixel information from a CMOS image sensor array using a combination of long and short integration periods, merging the data to produce wide dynamic range images, and optionally incorporating a medium integration period, with the ability to compare pixel information to a threshold to determine the final dynamic range, allowing for efficient dual exposure without the need for multiple sensors or precise timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple image sensors are used to increase dynamic range, then the dynamic range is improved, but the device cost and complexity increase
Solution Approach 1:
The pixel array is divided into multiple rows, where different rows perform different integration operations (long integration vs. short integration) simultaneously. This segmentation allows dual exposure functionality to be achieved within a single sensor array, eliminating the need for multiple sensors while maintaining wide dynamic range capability
Solution Approach 2:
The patent introduces a temporal dimension to the spatial pixel array by implementing different integration periods across different rows. Row 0 performs long integration while Row 1 performs short integration, and this pattern alternates across rows. This temporal-spatial multiplexing achieves multi-exposure functionality within a single sensor array
2Measurement precision
If sequential image acquisitions with different exposure settings are used, then the dynamic range is improved, but motion artifacts occur due to time delay between acquisitions
Solution Approach 1:
The patent implements periodic alternation of integration periods across different rows. Even rows (0, 2, 4, ...) perform long integration while odd rows (1, 3, 5, ...) perform short integration, creating a periodic pattern that captures multiple exposure levels simultaneously during a single scene exposure, eliminating motion artifacts
Solution Approach 2:
The patent maintains continuous operation of the entire pixel array during a single exposure event. All rows are exposed to the scene simultaneously, with different rows performing different integration operations in parallel, ensuring that the entire scene is captured at the same moment without temporal gaps that would cause motion artifacts
3Measurement precision
If dual exposure techniques are implemented, then the dynamic range is improved, but the buffer requirements and processing complexity increase
Solution Approach 1:
The patent merges the long integration and short integration results by selectively combining pixel data from different rows. For each column, pixels from rows with long integration (even rows) and pixels from rows with short integration (odd rows) are merged based on intensity thresholds, producing a single wide dynamic range image without requiring separate buffer storage for multiple complete images
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 minimizing buffer requirements, reducing noise, and achieving a wider dynamic range, potentially increasing the signal-to-noise ratio and improving image quality without the need for additional hardware or complex timing synchronization.
Implementation Method 1
a pixel array having a plurality of rows, each row having a plurality of pixels... to thereby produce wide dynamic range pixel information for each pixel of the first row
Data Source
AI summary
A method of increasing the dynamic range of a captured image using a pixel array having a plurality of rows includes reading first pixel information corresponding to a long integration period from each pixel of a first row, reading second pixel information corresponding to a short integration period from each pixel of the first row, and merging the first pixel information and the second pixel information to thereby produce wide dynamic range pixel information for each pixel of the first row. Reading first pixel information takes place during a first interval, reading second pixel information takes place during a second interval, and at least a portion of the second interval takes place during a long integration period corresponding to a second row of the pixel array.