Plenoptic Camera Birefringent Layer Color Acquisition
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Solution Overview
Problem
Current demosaicing processes in plenoptic cameras face challenges with accurate color conversion and geometric operations, leading to errors and artifacts due to poor calculation of interpolated color values, which impact full color image reconstruction.
Innovation Solution
The use of an electro-optical polarization modulator, specifically a birefringent medium that changes refractive indices based on polarization state, allows for enhanced color acquisition by capturing two images with different polarization states and subtracting one from the other to generate images with improved color intensity and reduced artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional demosaicing processes are used to reconstruct color images from plenoptic camera data, then color image reconstruction can be achieved, but color accuracy deteriorates due to poor calculation of interpolated color values and introduction of artifacts
Solution Approach 1:
The invention segments the color acquisition process by using a birefringent layer to separate light into ordinary and extraordinary rays, which are then captured by different photodetectors. This segmentation allows independent measurement of color components without relying on interpolated values from demosaicing, thereby improving color accuracy and eliminating artifacts.
Solution Approach 2:
The birefringent layer acts as an intermediary element between the main lens and the photodetector array. It modifies the optical path by splitting light based on polarization, enabling direct capture of color information without requiring post-processing demosaicing operations that introduce errors and artifacts.
2Loss of information
If a micro lens array is used to capture light field information, then directional and positional light data can be acquired, but color reconstruction quality deteriorates due to the complex demosaicing requirements
Solution Approach 1:
The photodetector array is segmented into different regions (ordinary ray photodetectors and extraordinary ray photodetectors) that capture different polarization components. This segmentation enables direct color measurement for each spatial location, preserving light field information while eliminating the need for error-prone demosaicing operations.
Solution Approach 2:
The invention changes the optical parameter being measured by introducing polarization discrimination through the birefringent layer. Instead of relying on spatial sampling and interpolation, the system directly measures color information through polarization-based separation, improving reconstruction quality while maintaining light field data integrity.
3Ease of operation
If demosaicing operations are performed on plenoptic data, then full color images can be generated, but geometric operation accuracy deteriorates due to poor calculation of interpolated color values
Solution Approach 1:
The birefringent layer serves as an optical intermediary that performs the color separation function before detection, eliminating the need for computational demosaicing. This approach maintains ease of operation for generating full color images while dramatically improving geometric operation accuracy by providing direct color measurements without interpolation errors.
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
This method achieves higher spatial resolution and richer color acquisition without introducing color artifacts, improving upon traditional demosaicing techniques by leveraging the properties of birefringent materials to refine color information capture.
Implementation Method 1
a controllable birefringent layer positioned in the image plane of the main lens and before the array of photodetectors onto which one micro-image (also called sub-image) is projected
Implementation Method 2
The use of an electro-optical polarization modulator, specifically a birefringent medium that changes refractive indices based on polarization state
Implementation Method 3
The use of an electro-optical polarization modulator, specifically a birefringent medium that changes refractive indices based on polarization state
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A system and method for generating multiple images with rich color acquisition using a plenoptic camera having a main lens disposed in front of a micro array of lenses, a mosaic color filter array and an image sensor, characterized in that it comprises: capturing a first set of images using an ordinary state of an electrically controllable birefringent medium being disposed between said main lens and said micro array of lenses, said ordinary state providing an ordinary ray to each pixel; capturing a second set of images using an extraordinary state of said electrically controllable birefringent medium, said extraordinary state splitting the light from said main lens into an ordinary ray and a extraordinary ray respectively impinging on two adjacent pixels of different colors, said extraordinary ray being shifted by distance of one pixel on said image sensor; performing a weighted subtraction of information about said second set of images from information about said first set of images; and generating a final set of images with rich color information from said weighted subtraction and said first set of images.