Pseudo-Digital Pixel Subsampling for Low-Distortion Image Readout
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Solution Overview
Problem
Current image subsampling techniques, such as analog and digital averaging, face challenges including increased routing complexity, color distortion, and the need for additional memory, particularly in digital averaging.
Innovation Solution
A pseudo-digital averaging method and apparatus that performs subsampling in the analog domain using individual signal quantization without final total quantization, allowing for a higher frame rate and reduced color distortion, achieved through k*k subsampling of pixel sets with noise reduction and conversion of signals into lower resolution digital signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital averaging is used for subsampling, then quantization precision is improved, but device complexity and memory requirements increase
Solution Approach 1:
The patent divides the subsampling process into two stages: first, multiple analog signals are averaged together in the analog domain; second, the averaged analog signal is quantized once in the digital domain. This segmentation allows quantization precision to be maintained while reducing the complexity of routing and memory requirements compared to quantizing each signal individually.
Solution Approach 2:
The patent introduces an analog averaging stage as an intermediary between signal acquisition and digital quantization. This intermediary process combines multiple analog signals before digital conversion, reducing the total number of quantization operations needed while preserving measurement precision through the averaging effect.
2Device complexity
If analog averaging is used for subsampling, then device complexity is reduced, but color distortion increases due to different sampling timings
Solution Approach 1:
The patent performs preliminary analog averaging of multiple pixel signals before digital quantization. By averaging the analog signals in advance and then quantizing the result once, the method eliminates color distortion issues that arise from different sampling timings in traditional analog averaging, while maintaining simplified device architecture.
3Measurement precision
If digital averaging with full resolution quantization is used, then measurement precision is improved, but productivity decreases due to lower frame rate
Solution Approach 1:
The patent applies partial quantization by performing quantization only once on the averaged analog signal rather than quantizing each individual signal at full resolution. This partial approach to quantization maintains sufficient measurement precision for the application while dramatically reducing processing time and increasing frame rate.
Data Source
AI summary
A method of k*k subsampling, where k is an integer greater than one, a full frame readout on a plurality of pixels arranged in rows and columns, each pixel belonging to one of at least two sets, a first set configured to sense a first value of an image parameter and a second set configured to sense a second value of the image parameter, the method including sampling signals of k pixels of at least one set in a first row to output subsampled signals, converting the subsampled signals into digital signals having a lower resolution than the full frame readout, repeating sampling and converting for k rows, and adding digital signals for the first to kth rows within the at least one set.