Focus Detection Device Adaptive Defocus Grouping
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Solution Overview
Problem
Existing focus detection systems struggle to accurately group defocus amounts for human subjects across varying photographing distances and focal lengths, leading to reduced focus detecting accuracy due to inconsistent differences in defocus amounts.
Innovation Solution
A focus detection device that includes a focus detector, object detector, selector, divider, and controller, which detects focus adjusting states, divides defocus amounts into groups based on variation using a calculated standard deviation and defocus width, ensuring that defocus amounts from the same human are accurately grouped together, regardless of photographing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If defocus amounts are divided into groups based on fixed thresholds, then grouping is simple to implement, but grouping accuracy deteriorates under varying photographing conditions
Solution Approach 1:
The patent applies dynamics by making the grouping threshold adaptive rather than fixed. The threshold is dynamically adjusted based on the standard deviation of defocus amounts, allowing the grouping criteria to change according to photographing conditions. This resolves the contradiction by maintaining implementation simplicity while improving grouping accuracy under varying conditions.
Solution Approach 2:
The patent changes the parameter used for grouping from a fixed threshold to a variable threshold based on statistical parameters (standard deviation). By using the standard deviation to determine grouping thresholds, the system adapts to different photographing scenarios while maintaining a consistent grouping methodology, thus improving accuracy without significantly complicating the implementation.
2Measurement precision
If multiple focus detecting areas are used to improve focus accuracy, then focus detecting accuracy is improved, but difficulty in detecting and measuring increases
Solution Approach 1:
The patent extracts the essential variation information from multiple defocus amounts by calculating the standard deviation. Instead of analyzing each individual defocus amount separately, the system extracts the key statistical parameter (standard deviation) that represents the overall variation, thereby simplifying the detection and measurement process while maintaining high accuracy.
Solution Approach 2:
The patent uses feedback by continuously monitoring the standard deviation of defocus amounts and adjusting the grouping strategy accordingly. The system feeds back the variation information to the grouping mechanism, allowing real-time adaptation to changing photographing conditions and maintaining optimal focus detection accuracy.
Data Source
AI summary
A focus detection device includes a focus detector, an object detector, a selector, a divider, and a controller. The focus detector is configured to detect a plurality of focus adjusting states at focus detecting positions in an image plane of an optical system. The object detector is configured to detect image information corresponding to a specified object in an image of the optical system. The selector is configured to select focus adjusting states among the plurality of focus adjusting states based on the image information detected by the object detector. The divider is configured to find variation in the selected focus adjusting states and configured to divide the selected focus adjusting states into a plurality of groups based on the variation. The controller is configured to find a final focus adjusting state based on a pre-final focus adjusting state in a group selected from the plurality of groups.