Dynamic Pixel Binning for Optical Biometric Imaging
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Solution Overview
Problem
Optical fingerprint sensors face a reduction in biometric performance due to increased object or image distance, leading to reduced image resolution, which affects the convenience and security of personal electronic devices.
Innovation Solution
A method of configuring an optical biometric imaging device by adjusting the binning of pixels to improve feature resolution, where the binning setting is dynamically adjusted based on measures of feature resolution to maintain optimal projected pixel size and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel binning is used to reduce data transfer amount, then data processing load is reduced, but image resolution deteriorates
Solution Approach 1:
The patent implements dynamic pixel binning adjustment where the binning factor is not fixed but varies based on real-time conditions. The system determines appropriate binning factors (e.g., 2x2, 4x4, 8x8) by analyzing image quality metrics and adjusts them frame-by-frame to optimize both data processing load and image resolution according to actual imaging conditions
Solution Approach 2:
The patent changes the binning parameter dynamically based on detected image quality and processing requirements. By adjusting the binning factor as a variable parameter rather than using a fixed value, the system can adaptively balance between reducing data volume and maintaining sufficient resolution for biometric identification
2Ease of operation
If object distance increases, then device portability is improved, but image resolution deteriorates
Solution Approach 1:
The patent employs feedback mechanisms where the system continuously monitors image quality metrics and adjusts binning settings based on real-time analysis. When image resolution deteriorates due to increased object distance, the feedback loop detects this and automatically adjusts the binning factor to compensate, maintaining acceptable image quality for biometric authentication
Solution Approach 2:
The system performs preliminary analysis of image quality parameters and proactively adjusts binning settings before significant resolution degradation occurs. By anticipating the impact of distance changes and pre-adjusting binning factors, the system maintains optimal imaging conditions without requiring physical repositioning
3Measurement precision
If projected pixel size is reduced to improve resolution, then image resolution is improved, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies partial binning strategies where instead of uniformly binning all pixels, the system selectively bins pixels based on local image characteristics and required resolution. This partial approach allows maintaining fine detail in critical regions while reducing binning in areas where it would excessively degrade signal quality
Solution Approach 2:
The patent implements non-uniform binning patterns where different regions of the image sensor apply different binning factors. Critical areas requiring high resolution use lower binning factors, while less critical areas use higher binning factors, creating local quality variations that optimize both resolution and signal-to-noise ratio across the entire image
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 method enhances biometric image resolution and performance by reducing the projected pixel size when necessary, ensuring that biometric features are resolvable, even with changes in object or image distance, thereby maintaining security and convenience in electronic devices.
Implementation Method 1
an image sensor comprising a photodetector pixel array
Implementation Method 2
employ micro-channels, i.e. collimators or microlenses to focus incoming light onto an image sensor
Data Source
AI summary
The present invention relates to a method of configuring an optical biometric imaging device comprising a photodetector pixel array, the method comprising: acquiring a biometric image of a biometric object using a first binning setting for binning of detection signals from subarrays of the photodetector pixels into a single pixel value; determining a measure indicative of the feature resolution of the biometric image; and determining, when the measure indicates that the feature resolution is below a feature resolution threshold, a second binning setting adapted to provide a higher feature resolution compared to the feature resolution of the biometric image.