Polarization Image Synthesis for Overexposure Suppression in Endoscopy
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Solution Overview
Problem
Existing imaging technologies struggle with overexposure and underexposure issues when capturing images with varying polarization states, particularly when observing subjects through glass or in high-contrast environments, leading to improper image capture.
Innovation Solution
An imaging apparatus with a polarization image sensor and image processing units that decompose and rank polarization components, using weighted averaging to generate composite RGB values based on brightness thresholds, suppressing overexposure and underexposure by synthesizing RGB values from different polarization components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a variable phase difference plate is used to acquire color images with different polarization states, then polarization information can be captured, but coloring is produced due to the variable phase difference plate
Solution Approach 1:
The patent extracts and removes the variable phase difference plate from the optical system, replacing it with a polarization image sensor that directly captures polarization information without introducing coloring artifacts. This eliminates the harmful effect while preserving the ability to measure polarization states.
Solution Approach 2:
The patent replaces the mechanical variable phase difference plate with an electronic/pixel-level solution using a polarization image sensor with microlenses and color filters. This substitution eliminates the mechanical component that causes coloring while maintaining polarization measurement capability through direct optical detection.
2Reliability
If multiple color images at different exposure conditions are synthesized to create HDR images, then overexposure and underexposure are suppressed, but the imaging system becomes more complex
Solution Approach 1:
The patent segments the imaging function into four distinct polarization components (0°, 45°, 90°, 135°) captured simultaneously by the polarization image sensor. This segmentation allows independent processing of each polarization channel to determine appropriate exposure and synthesis, simplifying the overall system compared to traditional multi-exposure HDR methods.
Solution Approach 2:
The patent performs preliminary ranking of polarization components by brightness before synthesis, identifying which components are overexposed or underexposed. This preliminary analysis enables selective use of appropriate polarization components for final image synthesis, preventing exposure issues without requiring multiple separate exposure shots.
3Productivity
If RGB values are directly synthesized from all polarization components, then processing is simplified, but overexposure and underexposure occur
Solution Approach 1:
The patent performs preliminary brightness ranking of all polarization components before synthesis. This preliminary action identifies which components are suitable for synthesis (those with appropriate brightness levels) and which should be excluded (overexposed or underexposed components), ensuring reliable exposure while maintaining efficient processing.
Solution Approach 2:
The patent applies different synthesis strategies to different polarization components based on their local brightness characteristics. Overexposed components are excluded from synthesis, underexposed components are enhanced, and appropriately exposed components are used as-is. This localized quality control ensures accurate exposure in the final synthesized image.
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
The solution effectively suppresses overexposure and underexposure, ensuring accurate image capture by adjusting RGB values based on polarization component rankings and brightness, resulting in improved image quality.
Implementation Method 1
a polarization image sensor in which pixel groups, each including 2×2 pixels for detecting four polarization components that vary depending on a pixel
Data Source
AI summary
An imaging apparatus includes: a polarization image sensor for detecting four polarization components; an interpolation processing unit that calculates, pixel by pixel, an RGB value of each of the four polarization components from the polarization image sensor; a rank processing unit that ranks the four polarization components; a reference generation unit that calculates a reference brightness value; and a synthesis processing unit that a) outputs a reference RGB value when the reference brightness value matches a predetermined threshold value, b) outputs a composite RGB value obtained by synthesizing a high-rank RGB value and the reference RGB value when the reference brightness value is smaller than the threshold value, and c) outputs a composite RGB value obtained by synthesizing a low-rank RGB value and the reference RGB value when the reference brightness value is greater than the threshold value.