Focus Control Apparatus Dynamic Area Segmentation
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Solution Overview
Problem
Existing autofocus control methods in image capturing apparatuses face challenges in maintaining stable focus control during live-view mode and moving image capture, especially with high-resolution imaging, as increased focus detection range can lead to difficulties in focusing on subjects with conflicting far and near points, and low light or low-contrast conditions degrade focus detection precision.
Innovation Solution
A focus control apparatus and method that divides the imaging surface into multiple areas in two directions, allowing for the combination of focus information from these areas to calculate defocus information and adjust focus control accordingly, improving precision and reliability by merging correlation amounts along the direction perpendicular to phase-difference detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the focus detection range is increased to improve stability during live-view mode and moving image capture, then focus control stability is improved, but it becomes difficult to bring the intended subject into focus when there is a conflict between far point and near point
Solution Approach 1:
The imaging surface is divided into multiple divided areas, and the focus detection range is further segmented into multiple focus detection areas within each divided area. This allows the system to selectively use different focus detection areas based on the image capturing state, resolving the contradiction between wide coverage for stability and localized precision for subject focus.
Solution Approach 2:
The number and configuration of focus detection areas are dynamically adjusted based on the image capturing state (such as live-view mode, moving image capture, low light conditions, low contrast conditions). This dynamic adaptation allows the system to optimize between stability and precision depending on the specific capturing scenario.
2Measurement precision
If the focus detection range is divided into multiple focus detection areas to improve focus precision, then focus detection precision is improved, but the signal-to-noise ratio is lowered in low light intensity conditions
Solution Approach 1:
The system dynamically adjusts the number of focus detection areas based on light intensity and contrast conditions. In low light or low contrast conditions, fewer focus detection areas are used to maintain adequate signal-to-noise ratio, while in optimal conditions, more areas are used for higher precision.
Solution Approach 2:
The system changes the parameter of the number of focus detection areas according to image capturing conditions (light intensity, contrast, capture mode). This parameter adjustment allows optimization of the balance between precision and signal quality under different conditions.
3Reliability
If signals from multiple divided areas are merged to reduce noise influence, then signal-to-noise ratio is improved, but the precision of focus detection may decrease due to averaging effects
Solution Approach 1:
The system segments the imaging surface into divided areas and further segments focus detection within each divided area. This hierarchical segmentation allows selective merging of signals from multiple areas while maintaining the ability to use individual area data when higher precision is needed.
Solution Approach 2:
The system selectively merges signals from only the necessary number of focus detection areas based on conditions, rather than always merging all available signals. This partial merging approach maintains adequate signal-to-noise ratio while preserving focus detection precision by avoiding excessive averaging.
Data Source
AI summary
A focus control apparatus, comprises an area setting unit that sets a plurality of divided areas by dividing in a first direction and in a second direction, the first direction corresponding to a direction in which a focus state is detected; a focus detection unit that detects first information related to the focus state; a calculation unit that calculates defocus information on the basis of the first information; and a control unit that performs focus control on the basis of the calculated defocus information, wherein in a first mode in which the defocus information for the focus control is calculated by combining pieces of the first information, the calculation unit causes the part of the plurality of divided areas to vary in accordance with pieces of the first information.