Image Sensor Inflection Point Correction
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Solution Overview
Problem
Existing image pickup apparatuses face challenges in correcting the variation of photoelectric conversion characteristics across pixels, particularly due to inflection point shifts caused by temperature changes, which affect image quality and require significant memory and computational resources for correction.
Innovation Solution
An image pickup apparatus with an image pickup device having pixels with different photoelectric conversion characteristics, utilizing a light shielding member and an image processing section that generates inflection point data and applies correction operations to align these characteristics with a standard photoelectric conversion characteristic, enabling real-time correction without the need for large memory storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photoelectric conversion characteristics of all pixels are divided into multiple illuminance areas with memorized data for correction, then correction precision is improved, but memory capacity requirement increases to 4 G Byte which is impractical for digital cameras
Solution Approach 1:
The patent extracts only the essential inflection point position data from the full photoelectric conversion characteristics, storing merely the inflection point positions rather than complete characteristic curves. This extraction reduces memory requirements from 4 G Byte to a practical size while maintaining correction precision through targeted storage of critical parameters.
Solution Approach 2:
The patent changes the correction approach from storing complete characteristic curves to storing only inflection point position parameters. By transforming the correction data into a parameter-based representation (inflection point positions) rather than full characteristic data, the system achieves efficient memory usage while preserving correction accuracy.
2Measurement precision
If complete photoelectric conversion characteristics are memorized for all pixels, then correction accuracy is improved, but computational complexity and operation time increase making the method unrealistic for digital cameras
Solution Approach 1:
The patent extracts only the inflection point position information from complete photoelectric conversion characteristics. By taking out only the essential inflection point data rather than processing full characteristic curves, the system reduces computational complexity while maintaining correction accuracy through targeted processing of critical parameters.
Solution Approach 2:
Instead of comparing complete characteristic curves as in conventional methods, the patent inverts the approach by comparing only inflection point positions. This inversion simplifies the correction process from complex curve-by-curve comparison to straightforward position-based correction, reducing operational time and computational load.
3Measurement precision
If parallel shift correction is applied to match logarithmic characteristics, then high illuminance area coincidence is improved, but inflection point variation cannot be corrected in lower illuminance areas
Solution Approach 1:
The patent applies local quality correction by treating inflection point correction separately for different illuminance regions. Instead of a uniform parallel shift, the system performs localized correction at inflection points across different illuminance areas, ensuring both high illuminance coincidence and lower illuminance accuracy through region-specific adjustment.
Solution Approach 2:
The patent performs preliminary detection of inflection point positions before executing correction operations. By detecting and storing inflection point positions in advance, the system prepares correction data that enables comprehensive correction across all illuminance areas, preventing the incomplete correction issue of conventional parallel shift methods.
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 improved image quality by correcting inflection point variations in real-time, reducing memory requirements and computational complexity, making it feasible for use in digital cameras.
Implementation Method 1
an image pickup device including a plurality of pixels which have a plurality of different photoelectric conversion characteristics different from each other on each side of an inflection point
Data Source
AI summary
In an image pickup apparatus including an image pickup device configured by a plurality of pixels having different photoelectric conversion characteristics on each side of the inflection point of the photoelectric conversion characteristic, prior to the image picking-up for recording, resetting the image pickup device twice by using different voltages with the image pickup device being light shielded, generating inflection point data showing an infection point by using imaged data obtained after reset operation, and afterward correcting the inflection points variation by using the inflection point data can correct the variation of the photoelectric conversion characteristic in a substantially real time. And it can provide a less expensive and high image quality image pickup apparatus and a method for taking a high quality image.