Autofocus Area Selection Using Dynamic Range and Reference Position Updates
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Solution Overview
Problem
Existing autofocus technologies struggle to accurately select an appropriate autofocus area when dealing with subjects that have a mix of near and far objects, often resulting in focus being set on the background instead of the main subject.
Innovation Solution
A focus adjustment device and method that repeatedly detect defocus amounts across multiple autofocus areas, using a processor with various sections to set ranges, convert defocus amounts, and update reference positions to select the most appropriate autofocus area based on focus target positions and reference positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If autofocus area selection is based on defocus amount using conventional methods, then the focusing process can be automated, but the main subject may be incorrectly focused when there is a mix of near and far objects
Solution Approach 1:
The patent segments the autofocus decision-making process into multiple independent evaluation stages: initial defocus amount detection, range determination based on focus target positions, reference position establishment, and final AF area selection. This multi-stage segmentation allows each stage to specialize in specific aspects of focus accuracy, resolving the contradiction between automation and precision by breaking down the complex automated selection into manageable, precise sub-tasks
Solution Approach 2:
The patent performs preliminary actions by detecting defocus amounts for all AF areas before final selection, calculating focus target positions in advance, and establishing reference positions based on multiple measurements prior to making the final autofocus decision. These preliminary actions ensure that when the automated selection occurs, it is based on comprehensive pre-analyzed data, thereby maintaining both automation and precision
2Speed
If the system selects an AF area based on simple defocus amount detection, then the processing speed is fast, but the selection accuracy deteriorates in complex scenes with mixed near and far subjects
Solution Approach 1:
The patent implements dynamic adaptation by adjusting the range determination criteria and reference position establishment based on the specific scene conditions detected during each autofocus operation. The system dynamically modifies its selection parameters according to the distribution of focus target positions and detected defocus amounts, allowing it to maintain high speed while adapting precision to match the complexity of the specific scene being photographed
Solution Approach 2:
The patent incorporates feedback mechanisms where the detected defocus amounts and focus target positions from previous measurements are used to refine subsequent AF area selections. The reference position is updated based on accumulated measurement data, and the range determination is adjusted according to feedback from multiple defocus detections, enabling the system to maintain speed while improving accuracy through iterative refinement
Data Source
AI summary
A focus adjustment method comprising setting a first range including at least one AF area, or a second range including the first range, every time the defocus amount is detected, selecting the first range or the second range based on a focus target position of an AF area included in the second range, and a reference position, updating the reference position based on the plurality of focus target positions of AF areas included in the range that has been selected, and the reference position, and selecting an AF area used in the focus adjustment from the plurality of AF areas, based on the plurality of focus target positions of AF areas included in the range that has been selected, and the reference position that has been updated.