Autofocus Lens Control via Sharpness Feedback
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Solution Overview
Problem
Existing image capturing systems face challenges in achieving optimal focusing results due to reliance on relational data that does not account for the installation environment of the camera.
Innovation Solution
The image capturing apparatus and method incorporate distance information and image analysis information to adjust the focal position of the focus lens, with a controller determining the reference position and adjusting the lens in increments, and using a sharpness graph to calculate a target position if errors are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the camera performs focusing based on relational data between distance to subject and focus lens position, then the focusing process is simplified and can be performed automatically, but the focusing accuracy deteriorates because the relational data does not account for installation environment factors
Solution Approach 1:
The system captures a test image at the reference focus position calculated from relational data, evaluates the sharpness of the subject in that image, and uses the sharpness evaluation result as feedback to determine whether to apply an error correction value. This feedback mechanism allows the system to verify the accuracy of autofocus and compensate for environmental factors, thereby resolving the contradiction between simplified operation and focusing accuracy.
2Device complexity
If the camera uses only distance information for focusing, then the device complexity is reduced, but the focusing accuracy deteriorates due to unaccounted installation environment factors
Solution Approach 1:
The system introduces a sharpness evaluation mechanism as an intermediary between distance-based reference position calculation and final focus determination. By using image sharpness as a mediator to detect errors in the reference position and apply corrective error values, the system maintains relatively simple device complexity while significantly improving focusing accuracy by accounting for installation environment factors.
3Speed
If the camera adjusts focus lens position in pre-set increments during time intervals between image frames, then the processing speed is improved and real-time focusing is achieved, but the manufacturing precision of focus positioning may be limited by the increment steps
Solution Approach 1:
The system performs preliminary focusing by adjusting the focus lens to a reference position calculated from relational data before capturing the final image. This preliminary action allows the system to achieve fast real-time focusing while the subsequent sharpness evaluation and error correction refine the focus precision, effectively resolving the contradiction between focusing speed and positioning precision.
Data Source
AI summary
An image capturing apparatus may include: an imager including a focus lens, the imager configured to generate an image of a subject; a distance determiner configured to determine a distance to the subject; a reference position calculator configured to calculate a reference position of the focus lens based on the distance to the subject; and a controller configured to adjust a focal position of the focus lens in a direction of the reference position, wherein the controller is further configured to determine whether any error is reflected in the reference position based on a calculated sharpness of the image corresponding to the focal position of the focus lens being at the reference position.