Optical Axis Detection in Plenoptic Imaging Systems
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Solution Overview
Problem
Plenoptic imaging systems face challenges in accurately aligning the optical axis with the microlens and sensor arrays due to optical aberrations, leading to shifts in disparity and other effects in the captured images, which complicates depth estimation and three-dimensional reconstruction.
Innovation Solution
A method is introduced to estimate the location of the optical axis by filtering the captured plenoptic image to reduce high-frequency components, using noise filtering, down-sampling, and low-pass filtering to determine the optical axis location, which can then be used to correct for optical aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging procedures are used in plenoptic imaging systems, then the system can capture images, but optical aberrations cause shifts in disparity and reduce measurement precision
Solution Approach 1:
The patent changes the parameter being measured from raw pixel coordinates to filtered image features. By applying low-pass filtering and superpixel aggregation, the system transforms the image data to emphasize low-frequency components that reveal the optical axis position, thereby improving measurement precision without adding physical calibration hardware
Solution Approach 2:
The patent introduces an intermediary processing step between image capture and optical axis determination. The low-pass filter and superpixel aggregation act as intermediaries that process the raw plenoptic image data, extracting the optical axis information while suppressing aberration-induced noise and high-frequency artifacts
2Measurement precision
If the optical axis is not accurately aligned with the microlens array, then the system structure remains simple, but depth estimation and three-dimensional reconstruction precision deteriorate
Solution Approach 1:
The patent performs preliminary determination of the optical axis position using filtered image processing before conducting depth estimation and three-dimensional reconstruction. By pre-calculating the optical axis location from the plenoptic image data itself, the system compensates for manufacturing misalignments and uses this corrected reference for subsequent precise measurements
Solution Approach 2:
The patent replaces mechanical alignment procedures with computational methods. Instead of physically adjusting the optical axis alignment through precise mechanical positioning, the system uses image filtering and digital signal processing to computationally determine and correct for misalignment, thereby achieving high precision without corresponding manufacturing precision
3Measurement precision
If high-frequency components are preserved in the plenoptic image, then image detail is maintained, but optical aberration effects and disparity shifts increase
Solution Approach 1:
The patent applies partial filtering by focusing only on the low-frequency components necessary for optical axis detection. The low-pass filter and superpixel aggregation selectively process only the portions of the image spectrum needed for alignment determination, preserving sufficient information for accurate optical axis detection while discarding high-frequency details that contribute to aberration artifacts
Solution Approach 2:
The patent segments the plenoptic image into superpixels, grouping adjacent pixels together. This segmentation reduces the impact of high-frequency noise and aberration-induced variations at pixel boundaries, while maintaining the overall structural information needed for optical axis detection. Each superpixel represents an aggregated measurement that is more robust to high-frequency disturbances
Data Source
AI summary
The location of the optical axis of a plenoptic imaging system is determined. In one approach, the plenoptic image is noise filtered, down-sampled, low-pass filtered, and again noise filtered. Slices through this image that have the highest power are used to determine the location of the optical axis. Once the location of the optical axis is determined, corrections for aberrations such as distortion can be applied.