Computational Pixel Imager Counters for High Dynamic Range Stereo Imaging
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Solution Overview
Problem
Conventional imaging technologies rely on analog CMOS and CCD arrays that lack advanced in-pixel processing capabilities, limiting their dynamic range and efficiency in digital imaging applications.
Innovation Solution
The development of computational pixel imagers (CPIs) with integrated circuits within each pixel for digitizing photocurrent signals and performing advanced signal processing, including multi-thread processing and infinite-dynamic-range sensing, to enhance imaging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional analog CMOS and CCD arrays are used for imaging, then the imaging system is simpler in structure, but the dynamic range and digital signal processing capabilities are limited
Solution Approach 1:
The pixel circuit is divided into multiple independent counters (first counter, second counter, third counter) that can operate simultaneously to perform different signal processing functions. Each counter handles specific tasks such as integrating photocurrent, subtracting background, or detecting modulation frequencies, allowing complex digital processing without overwhelming a single circuit unit.
Solution Approach 2:
The pixel circuit is designed with multiple counters that can be configured to perform various imaging functions including wide-area imaging, stereographic imaging, and high dynamic range imaging. The same counter structure can be adapted for different wavelengths (visible, SWIR, MWIR) by adjusting control signals, making the pixel universally applicable across multiple imaging modes.
2Productivity
If multiple counters are integrated in each pixel for concurrent processing, then signal processing efficiency is improved, but the pixel area increases
Solution Approach 1:
Multiple counter circuits are integrated within a single pixel footprint by sharing common circuit elements such as the photodetector, biasing lines, and control logic. The counters are arranged to overlap or share physical space, reducing the total area required compared to having separate processing circuits for each counter.
Solution Approach 2:
The pixel circuit utilizes three-dimensional integration techniques where counters are stacked or arranged in multiple layers above the photodetector plane. This vertical arrangement allows multiple processing functions to coexist within the same lateral pixel area, effectively increasing processing capacity without proportionally increasing the pixel footprint.
3Productivity
If in-pixel digitization and processing are implemented, then imaging efficiency is improved, but the manufacturing complexity increases
Solution Approach 1:
The pixel circuit operates by changing the operational state of counters based on control signals rather than requiring physically different circuit structures for different functions. By modifying timing parameters, gate signals, and integration periods, the same hardware can perform multiple imaging tasks, simplifying manufacturing while maintaining high imaging efficiency.
4Measurement precision
If high read-out rate is used for most significant bit, then infinite dynamic range sensing is achieved, but the data transmission bandwidth increases
Solution Approach 1:
Only the most significant bit (MSB) of the counter output is read out at high frequency to capture the dynamic range information, while less significant bits are read out at lower frequencies or processed locally. This extraction approach transmits only the critical high-order data that defines the dynamic range, reducing overall data transmission volume while maintaining sensing precision.
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
CPIs enable efficient digital signal processing within pixels, improving dynamic range and imaging efficiency by allowing concurrent image processing and high-resolution imaging across a wide range of wavelengths, including infrared.
Implementation Method 1
Each pixel may include a photodetector configured to detect light and to produce photocurrent signals from the detected light
Data Source
AI summary
A stereo imaging system includes an optical assembly and a computational pixel imager (CPI) having a plurality of pixels. Each pixel includes a light sensor and counters that convert a photocurrent from the light sensor to a digital signal. The optical assembly, which directs light from a light field to the CPI, includes an optical field combiner and first and second primary lens assemblies, which are configured to receive first and second portions of the light from the lightfield, respectively, and to direct the first and second portions of the light to the optical field combiner. The optical field combiner includes a modulator configured to modulate the first and second portions of the light and to direct modulated first and second portions of the light onto the CPI. The counters are configured to perform digital signal processing on the digital signal.