Image Sensor Pixel Grouping for Frame Rate and Quality
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Solution Overview
Problem
Current digital image sequence capture devices face challenges in achieving high image quality, spatial resolution, and temporal resolution simultaneously without incurring significant memory, computational, or hardware costs, and struggle to capture high dynamic range images without increasing pixel complexity.
Innovation Solution
A method for producing digital images from an image sensor array that involves alternately reading panchromatic and color pixels, using a rolling shutter readout with varying exposure durations, and combining pixel signals to enhance spatial and temporal resolution while maintaining low buffering and avoiding complex algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the frame rate is increased, then temporal resolution is improved, but exposure duration must be shortened which degrades image quality and increases noise
Solution Approach 1:
The image sensor array is segmented into multiple pixel groups, where each group captures images at different exposure durations. This allows the system to produce a high frame rate sequence using shorter exposure images while preserving the ability to generate higher quality images from longer exposure groups, thus resolving the contradiction between frame rate and image quality.
Solution Approach 2:
The patent implements periodic switching between different exposure duration modes for different pixel groups. By alternating between short and long exposure periods across multiple groups, the system maintains high temporal resolution while periodically capturing high-quality images with longer exposures, balancing frame rate and image quality requirements.
2Reliability
If exposure duration is extended to improve image quality, then noise is reduced, but frame rate decreases
Solution Approach 1:
The pixel array is divided into multiple groups that can operate with different exposure durations simultaneously. This segmentation allows the system to produce both high frame rate sequences (using shorter exposure groups) and high quality sequences (using longer exposure groups) from the same sensor array, resolving the trade-off between frame rate and image quality.
Solution Approach 2:
The patent dynamically changes the exposure duration parameter for different pixel groups based on the desired output sequence characteristics. By adjusting exposure time as a variable parameter across different groups, the system can optimize for either frame rate or image quality depending on the specific sequence being captured, eliminating the fixed trade-off.
3Measurement precision
If spatial resolution is improved by reducing pixel binning, then image detail is enhanced, but temporal resolution decreases due to readout constraints
Solution Approach 1:
The sensor array is segmented into multiple pixel groups that can be read out in an interleaved manner. This allows the system to read out individual pixels at high spatial resolution while maintaining high temporal resolution by distributing the readout load across multiple groups, thus resolving the contradiction between spatial and temporal resolution caused by readout bandwidth constraints.
4Reliability
If a dual-sensor camera is used to improve temporal resolution and noise reduction, then image quality is enhanced, but device complexity and cost increase
Solution Approach 1:
The patent makes a single image sensor array perform multiple functions that would traditionally require separate sensors. By configuring one sensor array with multiple pixel groups that can operate in different modes, the system achieves the capabilities of a dual-sensor camera (different exposure times, potential stereo vision) without the complexity and cost of multiple physical sensors.
5Reliability
If temporal noise reduction techniques are applied, then noise is reduced, but memory requirements and computational complexity increase
Solution Approach 1:
The patent performs preliminary noise reduction by capturing multiple images with different exposure durations and combining them during the capture process itself. This preliminary action reduces noise before the images need to be stored or processed further, decreasing the burden on memory and computational resources compared to applying complex temporal noise reduction algorithms after 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 enables the production of sequences with increased spatial and temporal resolution and improved image quality without additional lenses or sensors, while also extending dynamic range without increasing pixel complexity, thus overcoming the limitations of existing technologies.
Implementation Method 1
an image sensor array having a first group of pixels and a second group of pixels
Data Source
Figure 1
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Figure 3A
AI summary
A method for producing a digital image from pixel signals captured by an image sensor array is disclosed. The method includes: providing an image sensor array having at least two groups of pixels wherein the pixels of each group are uniformly distributed over the sensor; exposing the image sensor array to scene light and reading pixel charge from only the first group of pixels to produce a first set of pixel signals; after producing the first set of pixel signals, exposing the image sensor array, and then reading pixel charge from the second group of pixels and reading again pixels from the first group to produce a second set of pixel signals; and using the first and second sets of pixel signals to produce the digital image.