Polarization Modulator for Ghosting Reduction in Image Capture
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Solution Overview
Problem
Existing image pickup apparatuses face limitations in capturing images with polarization information due to the need for dedicated illumination, loss of resolution and color information, and complex control requirements, particularly with multiple variable retardation plates.
Innovation Solution
An image processing apparatus with a polarization modulator comprising a quarter waveplate, a variable retardation plate, and a polarizer, which captures multiple color images with different polarization states and uses color correction to generate a synthesized image with polarization information, simplifying the structure and reducing the need for complex control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a wire grid polarizer is used to extract polarization information from multiple pixels, then polarization information can be obtained, but resolution and color information are lost
Solution Approach 1:
The patent divides the polarization measurement function into multiple discrete retardation plates (first, second, and third retardation plates with different retardation values), where each plate captures polarization information at a specific retardation state. This segmentation allows the system to obtain complete polarization information while maintaining full-resolution color images from each plate, avoiding the information loss inherent in pixel-sharing approaches.
2Loss of information
If two variable retardation plates are used to obtain Stokes parameters, then polarization information can be acquired, but the structure becomes expensive and complicated
Solution Approach 1:
The patent segments the polarization measurement into three distinct retardation plates with fixed, different retardation values, eliminating the need for variable retardation plates and their complex control systems. Each plate is optimized for a specific retardation state, simplifying the overall structure while maintaining the ability to capture complete polarization information.
Solution Approach 2:
Instead of using variable retardation plates that require dynamic adjustment and complex control, the patent employs three fixed retardation plates with different retardation parameters. This approach changes the system from dynamic/variable to static/fixed, reducing control complexity while achieving the same measurement objective through parallel rather than sequential operation.
3Loss of information
If a polarization filter is attached to the lens front surface, then polarization effects can be obtained, but dedicated illumination is required which limits the object and image capturing condition
Solution Approach 1:
The patent segments the polarization measurement into multiple fixed retardation plates that can be integrated into the imaging system without requiring external dedicated illumination. Each plate captures images under different polarization states, allowing the system to obtain polarization information under various natural lighting conditions, thereby improving adaptability to different imaging scenarios.
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 solution allows for the generation of desired images with improved polarization information capture, reducing the influence of ghosting and maintaining color accuracy, while simplifying the apparatus structure and reducing costs.
Implementation Method 1
a polarization modulator comprising a quarter waveplate, a variable retardation plate, and a polarizer
Implementation Method 2
a polarization modulator comprising a quarter waveplate, a variable retardation plate, and a polarizer
Data Source
AI summary
An image processing apparatus includes a corrector configured to provide a color correction based on a reference image selected from a plurality of color images having different polarization states acquired by changing a retardation provided to light from an object, for a synthesized image generated with polarization information of the object obtained from the plurality of color images.