Focus Control Apparatus Using Bracket Imaging Correction
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Solution Overview
Problem
Existing focus control systems in image capturing apparatuses face challenges in accurately detecting the in-focus position due to environmental influences and manufacturing errors, leading to incorrect automatic focus adjustment correction values.
Innovation Solution
A focus control apparatus that includes a focus detection unit, a control unit, and a storage unit to detect defocus values, acquire reliability, and adjust focus positions using correction values based on multiple images captured at different focus positions, ensuring accurate focus adjustment even when the reliability of the selected image is low.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If phase difference detection method is used to detect defocus value, then automatic focus adjustment can be performed, but detection accuracy deteriorates due to environmental influences and manufacturing errors
Solution Approach 1:
The system captures multiple images at different focus positions, detects defocus values for each image, and uses this feedback information to calculate a correction value that compensates for detection errors. The correction value is then applied to improve the accuracy of automatic focus adjustment, creating a closed-loop feedback system that continuously refines focus detection accuracy.
Solution Approach 2:
The system performs preliminary focus bracket imaging to capture multiple images at different focus positions before final focus determination. By pre-capturing images with known defocus values and calculating correction values in advance, the system prepares compensatory data that can be applied to correct detection errors in the main imaging process.
2Measurement precision
If AF micro adjustment function is provided for user correction, then focus accuracy can be improved, but operational complexity increases due to repeated imaging and checking operations
Solution Approach 1:
The system automatically performs focus bracket imaging, detects defocus values, calculates correction values, and applies corrections without requiring manual user intervention for each step. The apparatus serves itself by autonomously executing the entire correction process, eliminating the need for users to repeatedly capture and check images manually.
Solution Approach 2:
The system pre-calculates correction values based on focus bracket images captured before the main imaging operation. By performing the correction value calculation in advance, the system eliminates the need for users to engage in repeated trial-and-error adjustments, simplifying the operational process while maintaining high focus accuracy.
3Measurement precision
If focus bracket imaging is performed to calculate AF correction value, then detection precision can be improved, but reliability deteriorates when defocus value detection errors occur
Solution Approach 1:
The system captures more images than the minimum single image, using multiple images with different defocus values. By acquiring excessive focus bracket images beyond what would be strictly necessary, the system creates redundancy that allows it to identify and compensate for detection errors, thereby maintaining high reliability even when individual defocus value detections are inaccurate.
Solution Approach 2:
The system performs preliminary detection of defocus values for multiple focus bracket images before final correction value determination. By pre-detecting defocus values for multiple images and comparing them, the system can identify outliers and calculation errors, ensuring that the final correction value is reliable even if individual detection attempts fail.
Data Source
AI summary
In an focus control apparatus, a focus detection unit detects a defocus value, a control unit controls focus position adjustment, a first acquisition unit acquires reliability of the defocus value, a storage unit stores images captured by an image sensor at an in-focus position based on the defocus value and other focus positions and the defocus value detected for each image, in association with each image, and a second acquisition unit acquires a first correction value to be used for correcting the focus position adjustment based on the defocus values of unselected images in a case where the reliability of the defocus value corresponding to a selected image is lower than a first threshold, wherein The control unit adjusts the focus position using the first correction value.