Image Shift Detection Using Saturation-Aware Correlation Control
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Solution Overview
Problem
Existing image processing apparatuses face challenges in accurately determining the image shift amount due to image shape deterioration caused by saturation in pupil-divided images, leading to deteriorated focus detection precision and potential inability to perform focus detection.
Innovation Solution
An image processing apparatus comprising a correlation operation unit, saturation detection unit, and controller to manage the correlation of image signals from photoelectric conversion units, excluding the influence of saturation by controlling the correlation operation based on saturation detection results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If all signals of photoelectric conversion units corresponding to the same microlens are added together, then the image signal output is improved, but the linear characteristic deteriorates due to saturation influence
Solution Approach 1:
The patent divides the photoelectric conversion units into multiple groups corresponding to different microlenses, and processes signals from each group separately rather than adding all signals together. This segmentation allows the system to maintain linear characteristics by preventing saturation from propagating across the entire signal output.
Solution Approach 2:
The patent extracts and identifies saturated signals from the photoelectric conversion units and excludes them from the final image signal calculation. By removing the harmful saturated components, the system preserves the linear characteristic of the remaining unsaturated signals while maintaining adequate signal output.
2Productivity
If saturated pixels are included in correlation calculation, then the image processing continues, but the focus detection precision deteriorates
Solution Approach 1:
The patent performs preliminary saturation detection on photoelectric conversion units before incorporating their signals into the correlation calculation for focus detection. This preliminary action identifies and excludes saturated pixels from the correlation computation, ensuring that only valid signals contribute to the focus detection precision.
Solution Approach 2:
The patent implements a feedback mechanism where saturation detection results are used to control the correlation operation. Based on the saturation status of individual pixels or regions, the system dynamically adjusts which signals are included in the correlation calculation, thereby maintaining focus detection precision while continuing image processing.
3Productivity
If charge leaked from saturated pixels is included in the image signal, then the image processing completes, but the image shape deteriorates
Solution Approach 1:
The patent extracts and removes charge leakage components from saturated pixels before they can contaminate the image signal. By separating and eliminating these erroneous signals, the system preserves the integrity of the image shape while still completing the image processing operation.
Solution Approach 2:
The patent introduces an intermediary processing stage between the photoelectric conversion and the final image signal generation. This intermediary stage includes saturation detection and signal filtering, which prevents charge leakage from saturated pixels from directly affecting the image shape while allowing the processing to complete.
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
Enables accurate determination of image shift amounts even in cases of image shape deterioration due to saturation, improving focus detection precision and preventing false in-focus decisions.
Implementation Method 1
an image pickup element in which a plurality of photoelectric conversion units correspond to one microlens
Data Source
AI summary
An image processing apparatus processes image signals obtained from an image pickup element. A correlation operation unit operates a correlation of the image signals of two images that are obtained from the image pickup element and operates an image shift amount between images that are picked up by photoelectric conversion units, on the basis of the correlation. A saturation detection unit detects whether an image signal, of the two images, reaches a saturation level, and produces a saturation detection result. A controller controls the correlation operation unit such that the controller controls whether the correlation of the image signals from a plurality of photoelectric conversion units, including the photoelectric conversion units, is used for the operation of the image shift amount performed by the correlation operation unit. The control by the controller is made in accordance with the saturation detection result produced by the saturation detection unit.