Autofocus Detection Area Switching for Camera Subjects
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Solution Overview
Problem
Existing autofocus technologies in image capturing apparatuses face challenges in maintaining accurate focus when the subject is moving or still, particularly due to variations in face detection results caused by changes in luminance or noise, leading to inconsistent focus detection.
Innovation Solution
An image capturing apparatus that includes a detection unit, a focus adjusting unit, and a setting unit, which sets the focus detection area based on the position of the face when the subject is moving and the position of the eyes when the subject is still, ensuring accurate focus adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If face detection results are used directly for AF frame setting, then AF control can be performed, but detection variation occurs between frames due to changes in luminance or noise, leading to inaccurate focus
Solution Approach 1:
The patent applies preliminary action by performing face detection and determining the AF frame setting in advance before actual focus detection. By pre-establishing the AF frame based on face detection results, the system ensures that focus detection is performed on a stable, predetermined area, avoiding the instability that would occur if the AF frame were determined after focus detection or changed frequently during the process.
Solution Approach 2:
The patent applies dynamics by adaptively changing the AF frame setting method based on the subject's movement state. When the subject is detected as moving, the system uses face position-based AF frame setting; when the subject is still, it uses eye position-based setting. This dynamic adaptation allows the system to optimize focus detection accuracy according to the specific situation, resolving the contradiction between maintaining AF control and ensuring detection precision.
2Measurement precision
If the AF frame is set based on eye position, then accurate focus can be achieved for still subjects, but detection variation occurs when the subject is moving due to changes in face direction
Solution Approach 1:
The patent applies dynamics by switching between different AF frame setting methods based on the subject's movement state. For still subjects, it uses eye position-based setting to achieve accurate focus; for moving subjects, it switches to face position-based setting to maintain detection consistency. This dynamic selection resolves the contradiction between achieving high precision for still subjects and maintaining reliability for moving subjects.
Solution Approach 2:
The patent applies parameter changes by modifying the basis for AF frame setting (from eye position to face position) according to the subject's movement state. This parameter change allows the system to adapt to different scenarios: using eye position for still subjects to achieve precise focus, and using face position for moving subjects to ensure consistent detection despite changes in face direction.
3Measurement precision
If contrast AF is used alone, then focus can be adjusted, but the process is slow compared to phase difference AF
Solution Approach 1:
The patent applies merging by combining face detection technology with contrast AF. The face detection component provides rapid subject localization and AF frame setting, while the contrast AF component performs the actual focus adjustment. This combination allows the system to benefit from the speed of face detection and the accuracy of contrast AF, resolving the contradiction between focus detection accuracy and adjustment time.
Data Source
AI summary
An image capturing apparatus comprises a detection unit configured to detect a subject, a focus adjusting unit configured to adjust a position of a focusing lens of an imaging optical system so as to focus the imaging optical system on the subject, and a setting unit configured to set a focus detection area, which is an area within an image capturing screen where the focus adjusting unit detects focus, based on detection results of the detection unit, wherein the setting unit sets the focus detection area based on the position of the face of the subject in a case where the subject is moving, and sets the focus detection area based on the position of the eye of the subject in a case where the subject is still.