Multi-exposure Pixel Pattern for Dynamic Range
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Solution Overview
Problem
Digital cameras face limitations in dynamic range due to reduced light sensitivity and pixel miniaturization, leading to images that are either under-exposed or over-exposed, and existing methods for enhancing dynamic range are either costly or challenging algorithmically.
Innovation Solution
A multi-exposure pixel pattern where pixels are interleaved with different exposure times, allowing for weighted combination of exposure values to construct enhanced images, using a CMOS image sensor with pre-set exposure intervals and user-adjustable parameters for optimal dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple images are captured at different exposures and combined, then dynamic range is enhanced, but image registration complexity increases
Solution Approach 1:
The image sensor is divided into multiple pixel groups, where each group captures the same scene at a different exposure time. This segmentation allows different exposure levels to be obtained simultaneously without requiring image registration, as all pixels capture the same moment in time.
Solution Approach 2:
The exposure times for different pixel groups are predetermined and fixed before image capture. This preliminary setting of exposure parameters eliminates the need for post-capture registration operations, as the multi-exposure data is already prepared in the correct spatial relationships.
2Reliability
If beam splitters and multiple sensors are used for simultaneous multi-exposure, then registration is eliminated, but device cost and complexity increase
Solution Approach 1:
A single image sensor is used to perform multiple functions by capturing different exposure levels simultaneously through pixel group segmentation. This eliminates the need for multiple separate sensors and complex optical elements like beam splitters, reducing device cost and complexity while maintaining registration accuracy.
Solution Approach 2:
Instead of using multiple physical sensors to capture simultaneous multi-exposure images, the patent creates virtual copies of the same sensor data at different exposure levels by segmenting pixels. This software-based approach replaces expensive hardware multi-sensor systems.
3Adaptability or versatility
If fuzzy exposure mechanism is used to extend dynamic range, then exposure flexibility improves, but noise levels become incoherent across the image plane
Solution Approach 1:
Different pixel groups are assigned different fixed exposure times based on their local position in the sensor array. This creates spatially varying exposure characteristics that are predetermined and consistent, allowing each region to optimize its exposure while maintaining coherent noise characteristics across the entire image through simultaneous capture.
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 improves image quality by balancing exposure levels, reducing noise, and enhancing dynamic range without the need for image registration, offering a cost-effective and robust solution for both still images and video output.
Implementation Method 1
an image is captured with a multi-exposure pixel pattern... a plurality of groups of pixels of the image sensor have different exposure times
Data Source
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AI summary
Method, apparatus and software product for enhancing a dynamic range of an image with a multi-exposure pixel pattern taken by an image sensor (e.g., of a camera) for one or more color channels, wherein a plurality of groups of pixels of the image sensor have different exposure times (e.g., pre-selected or adjusted by a user through a user interface using a viewfinder feedback, or adjusted by a user through a user interface after taking and storing RAW image, etc.). Processing of the captured image for constructing an enhanced image of the image for each of the one or more color channels may be performe using weighted combination of exposure times of pixels having different pre-selected exposure times according to a predetermined criterion.