2PD Image Sensor Liveness Detection via Phase Imaging
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Solution Overview
Problem
Existing electronic devices using face recognition for security face challenges in effectively distinguishing between real and fake faces, especially in dark environments and when the boundary of a spoofing object is not fully included in the image.
Innovation Solution
The use of a 2PD image sensor in an electronic device to capture phase images and image data, which allows for precise liveness detection by calculating depth information and applying liveness models to authenticate external objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ToF sensor is added to enhance liveness detection performance, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple photodiodes (first and second photodiodes) within a single pixel structure to simultaneously capture light signals for both imaging and depth information. This merging approach enables the system to obtain phase images and liveness detection data without adding separate ToF sensors, thereby improving measurement precision while avoiding increased device complexity
Solution Approach 2:
The image sensor is designed to serve multiple functions: capturing standard images for recognition and simultaneously capturing phase information for depth calculation and liveness detection. By making the image sensor universal, the patent eliminates the need for dedicated depth-sensing hardware, thus improving measurement precision without increasing device complexity
2Measurement precision
If an IR LED and IR receiver are added for liveness detection, then measurement precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the liveness detection function into the existing image sensor by utilizing multiple photodiodes per pixel. This eliminates the need for separate IR LED and IR receiver components, thereby improving measurement precision while maintaining ease of manufacture
Solution Approach 2:
The patent extracts only the essential functionality needed for liveness detection (light signal capture and phase measurement) and integrates it into the image sensor's existing photodiode structure. This extraction approach removes the need for additional IR-specific components, improving measurement precision without increasing manufacturing complexity
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 electronic device achieves high-precision liveness detection and face recognition using a single camera module with a 2PD image sensor, enhancing security functions while reducing costs associated with additional sensors.
Implementation Method 1
Each pixel included in the plurality of pixels may include a plurality of photodiodes and a microlens covering the plurality of photodiodes
Implementation Method 2
obtain phase images and image data for an external object using the plurality of photodiodes of the image sensor
Data Source
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AI summary
An electronic device is provided. The electronic device includes a camera including an image sensor including a plurality of pixels, a memory, and a processor that controls the camera. Each pixel included in the plurality of pixels includes a plurality of photodiodes and a microlens covering the plurality of photodiodes. The processor obtains phase images and image data for an external object using the plurality of photodiodes of the image sensor and authenticates the external object using the phase images and the image data. In addition, various embodiments recognized through the specification are possible.