Image Sensor Pixel Array Dynamic Exposure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Consumer electronics cameras struggle to capture high-dynamic-range images effectively due to the challenge of varying luminosity in scenes, often resulting in under-exposed or over-exposed regions, leading to low signal-to-noise ratios and saturation issues.
Innovation Solution
A method involving an image sensor with a pixel array that adjusts exposure values for different pixel subarrays based on captured image data, determining an exposure count and setting pixels to multiple exposure values, allowing for capturing a second image that balances luminosity across varying scene regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single exposure value is used for the entire pixel array, then the device complexity is reduced, but the image quality deteriorates due to under-exposure or over-exposure in regions with varying luminosity
Solution Approach 1:
The patent applies local quality by assigning different exposure values to different spatial regions of the pixel array. Specifically, the image sensor divides the pixel array into multiple regions (e.g., first region with first exposure value, second region with second exposure value) and captures images with different exposure settings for each region. This allows each region to be optimally exposed according to its local luminosity characteristics, resolving the contradiction between simple exposure control and high image quality.
2Measurement precision
If multiple exposure values are applied to different pixel regions, then the signal-to-noise ratio is improved, but the device complexity increases due to multiple exposure settings
Solution Approach 1:
The patent applies segmentation by dividing the pixel array into multiple distinct regions, where each region is assigned a specific exposure value. The processor segments the captured image data according to these regions and processes each segment with its corresponding exposure characteristics. This segmentation approach enables improved signal-to-noise ratio through multiple exposure values while managing device complexity through systematic region division and processing.
3Reliability
If the exposure value is increased for bright regions, then over-exposure is reduced, but the signal-to-noise ratio deteriorates in those regions
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the exposure value parameter for different spatial regions of the pixel array. The processor determines appropriate exposure values for each region based on scene luminosity characteristics, then modifies the exposure parameter accordingly. This allows bright regions to use shorter exposure times (reducing over-exposure) while dark regions use longer exposure times (improving signal-to-noise ratio), resolving the contradiction between exposure accuracy and signal quality.
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 capture of high-dynamic-range images by optimizing exposure settings for each pixel subarray, reducing under-exposure and over-exposure issues, thereby improving signal-to-noise ratios and image quality across diverse luminosity regions.
Implementation Method 1
an image sensor that includes a pixel array... each of the plurality of pixel values having been generated by a respective one of a first plurality of pixels
Data Source
AI summary
A method for capturing a high-dynamic-range image includes: (i) storing a plurality of pixel values representing a first image captured by an image sensor that includes a pixel array, each pixel value having been generated by a respective pixel of a pixel subarray of the pixel array, each pixel being set to one of N1 first exposure values, N1≥1; (ii) determining an exposure-count N2 based on the plurality of pixel values; (iii) setting each pixel to one of a second plurality of exposure values, N2 in number, such that, for each of the second plurality of exposure values, at least one pixel is set to that exposure value, one of the second plurality of exposure values differing from each of the N1 first exposure values by more than a threshold value; and after setting (iv), capturing a second image with the image sensor.