Image Sensor Pixel Saturation Handling via Infrared Subtraction
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Solution Overview
Problem
Image pickup devices, such as CCDs and CMOS sensors, experience low color reproducibility and noise due to the mixing of visible and infrared light signals, leading to saturation issues that result in an undue darkening of pixel values and a white-out effect when infrared light components are subtracted from saturated pixels.
Innovation Solution
An image pickup apparatus comprising first pixels that receive both visible and infrared light, second pixels that receive only infrared light, and a processing unit that estimates the visible light component using the output signals from adjacent unsaturated pixels, allowing for accurate subtraction of infrared light components and reduction of noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared light components are subtracted from saturated pixel values, then color reproducibility is improved, but pixel values become unduly dark and noise appears
Solution Approach 1:
The patent applies preliminary action by detecting pixel saturation status before performing infrared light subtraction. The processing unit identifies saturated pixels and excludes them from the subtraction operation, preventing the undue darkening and noise generation that would otherwise occur. This preliminary detection and conditional processing resolves the contradiction by ensuring subtraction is only performed on unsaturated pixels where it improves color reproducibility without harming pixel value accuracy.
2Use of energy by moving object
If infrared cut filter is not used, then image pickup device sensitivity is maintained, but visible light and infrared light mix causing low color reproducibility
Solution Approach 1:
The patent applies segmentation by separating the handling of visible light and infrared light signals through dedicated pixel types. First pixels capture both visible and infrared light, while second pixels capture only infrared light. The processing unit then processes these segmented signals differently - subtracting infrared components from first pixels to improve color reproducibility while maintaining overall device sensitivity.
Solution Approach 2:
The patent extracts the infrared light component from the combined visible and infrared signal captured by first pixels. By using second pixels to measure infrared light separately and subtracting this extracted infrared component from the first pixel signals, the system removes the harmful infrared influence on color reproduction while preserving the benefits of not using an infrared cut filter.
3Ease of operation
If pixel values are processed without saturation detection, then processing simplicity is maintained, but saturated pixels produce noise and white-out effect
Solution Approach 1:
The patent implements feedback by continuously monitoring pixel saturation status and using this information to control the infrared light subtraction process. The processing unit receives feedback about which pixels are saturated and adjusts its processing accordingly - applying subtraction only to unsaturated pixels and excluding saturated pixels from this operation. This feedback mechanism eliminates noise and white-out effects while maintaining reasonable processing complexity.
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 approach enables the generation of images free from the white-out effect and noise, with improved accuracy in estimating visible light components, thereby enhancing image quality and reducing unnecessary darkening caused by excessive infrared light subtraction.
Implementation Method 1
image pickup devices such as CCDs (Charge-Coupled Device) and CMOS (Complementary Metal-Oxide Semiconductor) sensors have sensitivity in not only visible light but also infrared light
Data Source
AI summary
A plurality of first pixels receive both visible light and infrared light. A plurality of second pixels receive infrared light. A ratio calculation unit calculates the ratio of an output signal of another first pixel different from saturated first pixel and an output signal of a second pixel corresponding to the another first pixel. A signal estimation unit multiplies the output signal of a second pixel corresponding to the saturated first pixel, by the ratio calculated by the ratio calculation unit. A subtractor subtracts the output of a second pixel corresponding to the saturated first pixel, from a signal estimated as an output signal of the saturated first pixel.