Color Filter Array Blocks for Low-Light Binning and Demosaicing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image sensors face challenges in enhancing low light performance and de-mosaicing efficiency, particularly in high pixel count scenarios, where interpolation and extrapolation processes are suboptimal and signal-to-noise ratio (SNR) is limited.
Innovation Solution
A pixel array design with a color filter array (CFA) configuration that includes specific patterns of pixels for each color, particularly emphasizing a higher green pixel ratio and surrounding green shells, enabling improved light sensitivity and facilitating efficient binning and de-mosaicing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a higher pixel count is used in the pixel array, then image resolution is improved, but signal-to-noise ratio (SNR) deteriorates and low light performance worsens
Solution Approach 1:
The pixel array is segmented into multiple CFA blocks with different color filter configurations (first CFA blocks with first color filters, second CFA blocks with second color filters, third CFA blocks with third color filters). This segmentation allows different regions to specialize in capturing different color information, improving overall SNR while maintaining high resolution through the mosaic pattern.
Solution Approach 2:
Multiple CFA blocks of the same color type are merged together to form binned pixels. By combining signals from adjacent pixels of the same color, the patent achieves higher SNR in low light conditions while preserving the ability to maintain high resolution when needed through the de-mosaicing process.
2Ease of manufacture
If a traditional Bayer CFA pattern is used, then manufacturing simplicity is maintained, but de-mosaicing efficiency and image quality deteriorate
Solution Approach 1:
Instead of using a uniform Bayer pattern throughout, the patent applies different CFA patterns to different blocks (first, second, and third CFA blocks with different color filters). This local variation optimizes color capture in different regions, improving de-mosaicing efficiency and image quality while maintaining compatibility with standard manufacturing processes.
Solution Approach 2:
The patent creates a composite CFA structure by combining multiple types of CFA blocks (first CFA blocks, second CFA blocks, third CFA blocks) in a mosaic arrangement. This composite approach leverages the strengths of different color filter configurations to achieve superior overall performance compared to a single uniform pattern.
3Reliability
If binning is applied to increase SNR, then low light performance is improved, but image resolution deteriorates
Solution Approach 1:
The patent enables dynamic switching between binned and unbinned modes. In low light conditions, binning is applied to improve SNR by combining signals from multiple pixels. In brighter conditions, the full resolution can be maintained by processing individual pixels separately through de-mosaicing, thus dynamically adapting to lighting conditions to optimize both SNR and resolution.
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
The CFA+ pattern enhances low light capabilities, improves SNR, and simplifies de-mosaicing by providing better reconstruction of color channels, resulting in higher image quality and power efficiency.
Implementation Method 1
Image sensors generate an image of an object using a photoelectric conversion element, which reacts to the intensity of light reflected from the object
Data Source
AI summary
A pixel array of an image sensor includes a plurality of color filter array (CFA) cells. Each of the plurality of CFA cells includes first, second, third, and fourth CFA blocks. Each of the first and second CFA blocks includes a plurality of pixels to sense light of a first color. Most pixels of the third CFA block are configured to sense the second color and the third CFA block includes at least one first pixel to sense the first light. Most pixels of the fourth CFA block are configured to sense a third color of light and the fourth CFA block includes at least one second green pixel to sense the first light.