Dual Region Autofocus Controller for Low Contrast Video
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Solution Overview
Problem
Existing imaging devices face challenges in achieving stable and accurate autofocus during moving image capture, particularly when subjects have low contrast, leading to potential lens movement issues and reduced image quality.
Innovation Solution
The imaging device employs a dual focus adjustment region approach, where a first region with high priority and a second region with lower priority are used for focus adjustment, with the controller determining the difficulty of focus adjustment in the first region and switching to the second region if necessary, and vice versa, to maintain stability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus adjustment is performed based on image data from a single primary region, then focusing accuracy for the main subject is improved, but focusing fails when the subject has low contrast in that region
Solution Approach 1:
The imaging device divides the image into multiple focus adjustment regions (first region with high priority and second region with lower priority). This segmentation allows the system to attempt focus adjustment in the primary region first, and if that fails (low contrast), switch to the secondary region, thereby resolving the contradiction between accuracy and reliability.
Solution Approach 2:
The system preliminarily evaluates the contrast in the first focus adjustment region before performing focus adjustment. If the contrast is insufficient, it prepares and executes focus adjustment using the second region instead, preventing focusing failure before it occurs.
2Speed
If focus adjustment is performed rapidly to maintain autofocus during moving image capture, then responsiveness is improved, but unnecessary lens movement occurs leading to reduced image quality
Solution Approach 1:
The focus adjustment system dynamically adapts its behavior based on the detected subject state. When a subject is detected in the first region, rapid focus adjustment is performed. When no subject is detected or contrast is low, the system switches to using the second region, adjusting the focus speed and movement characteristics to prevent unnecessary lens movement while maintaining responsiveness when needed.
Solution Approach 2:
The system continuously evaluates image data from multiple regions to determine the appropriate focus adjustment strategy. Based on this feedback about subject presence and contrast levels, it dynamically selects which region to use for focus adjustment, thereby maintaining both speed and stability.
Data Source
AI summary
An imaging device includes an imaging section, an image capture optical system, and a controller. The controller sets in an image a first focus adjustment region, which is a target of adjustment of focusing conditions, and a second focus adjustment region, which has a lower priority of adjustment of focusing than the first focus adjustment region. The controller performs focus adjustment based on the image data in the second focus adjustment region, if focus adjustment based on the image data in the first focus adjustment region is difficult. If the focus adjustment based on the image data in the first focus adjustment region is not difficult, while performing the focus adjustment based on the image data in the second focus adjustment region, the controller performs the focus adjustment based on the image data in the first focus adjustment region.