Focus Detection Area Selection Using Reliability Assessment
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Solution Overview
Problem
Existing focus detection methods, particularly in imaging plane phase difference detection, face challenges with perspective conflicts when using large focus detection areas, leading to erroneous distance measurement and potential focusing on unintended objects due to low-contrast image signals and small focus detection areas.
Innovation Solution
A focus detection apparatus that sets multiple focus detection areas, including a first and second area, with the second area positioned near the first, allowing for focus detection reliability assessment. If the first area's reliability is low and the second area's reliability is high, the second area is used as a third focus detection area to reduce perspective conflicts by ensuring accurate focus detection on the intended object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large focus detection area is used to improve focus detection reliability, then the possibility of perspective conflict increases, but if a small focus detection area is used to avoid perspective conflict, then focus detection may fail due to low-contrast image signals
Solution Approach 1:
The image is divided into multiple focus detection areas (first, second, and third focus detection areas) with different sizes and positions. The system segments the detection task across multiple areas and selects the most appropriate one based on reliability assessment, rather than using a single large area that causes perspective conflict or a small area that may fail detection.
Solution Approach 2:
The system dynamically changes the parameters of the focus detection area (size, position, shape) based on the detected object's characteristics and reliability metrics. By adjusting the area parameters according to the specific imaging conditions, the system optimizes both detection reliability and measurement precision without suffering from perspective conflict.
2Measurement precision
If focus detection is performed with a small focus detection area, then perspective conflict is avoided, but focus detection may fail due to low-contrast image signals
Solution Approach 1:
The system segments the focus detection task into multiple areas with different characteristics. When a small area is used to avoid perspective conflict, the system supplements it with adjacent areas to ensure sufficient signal contrast for reliable detection.
Solution Approach 2:
The system merges multiple focus detection areas (first, second, and third areas) into a unified detection framework. By combining the results from multiple areas, the system achieves both the precision benefits of smaller areas and the reliability benefits of larger effective detection coverage.
3Reliability
If focus detection area is extended in focus detection direction to perform focus detection on a large area, then focus detection failure is avoided, but the range captured increases causing perspective conflict
Solution Approach 1:
Instead of using one large focus detection area, the system segments the detection into multiple smaller areas (first, second, third focus detection areas) with different sizes and positions. This segmentation allows the system to achieve reliable detection without capturing objects at different distances that would cause perspective conflict.
Solution Approach 2:
The system applies local quality by creating focus detection areas with different characteristics suited to different local conditions. The first, second, and third areas have different sizes and positions optimized for specific detection scenarios, allowing reliable focus detection without the need to extend a single large area that would introduce perspective conflict.
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 effectively reduces perspective conflicts and improves focus detection accuracy by selecting the most reliable focus detection area, ensuring precise focusing on the intended object while minimizing the influence of objects at different distances.
Implementation Method 1
an image sensor including a plurality of photoelectric conversion units and configured to output a pair of parallax image signals and an imaging signal
Data Source
AI summary
A focus detection apparatus includes a first setting unit configured to set a first focus detection area and a second focus detection area, a first focus detection unit configured to perform focus detection of a phase difference detection method on each of the first and second focus detection areas by using the pair of parallax image signals, a reliability acquisition unit configured to obtain reliability of the focus detection of the first and second focus detection areas by the first focus detection unit, a second setting unit configured to determine a third focus detection area by using the reliability of the focus detection of the first and second focus detection areas, obtained by the reliability acquisition unit, and a second focus detection unit configured to perform focus detection by using the third focus detection area.