Macro Autofocusing Using Multiple Focus Perimeters
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Solution Overview
Problem
Existing electronic devices with cameras face challenges in autofocusing macro objects, as conventional autofocus mechanisms often fail to determine optimal lens positions for both foreground and background objects, leading to suboptimal focusing results when small objects are close to the camera lens.
Innovation Solution
The method involves using phase detection autofocus mechanisms with multiple focus perimeters on the viewfinder, where focus values are obtained and compared to identify the macro object focus value, allowing the processor to determine and adjust lens settings for optimal focusing of the nearest object, while also considering other objects in the scene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the imaging device uses conventional autofocus mechanisms that average distances between foreground and background objects, then the lens position is determined based on averaged distance, but the resulting lens position is not optimal for focusing either the foreground object or the background scene
Solution Approach 1:
The patent divides the viewfinder into multiple focus perimeters (first, second, third, and fourth focus perimeters) that correspond to different depth zones. Each perimeter is associated with specific depth values representing different distance ranges from the camera. This segmentation allows the system to evaluate focus metrics independently for each depth zone rather than averaging across all depths, enabling precise focusing on foreground macro objects while maintaining the ability to focus on background scenes when needed.
2Ease of operation
If the imaging device focuses on the averaged distance between foreground and background, then the lens position is compromise, but neither the foreground macro object nor the background scene is optimally focused
Solution Approach 1:
The patent implements a feedback mechanism where the processor calculates focus metrics for multiple focus perimeters at different depth zones, compares these metrics, and determines the optimal lens position based on the comparison. The system uses phase detection autofocus to provide feedback about focus quality for each perimeter, then adjusts the lens position accordingly. This feedback loop enables the device to automatically select and focus on the most important subject (such as a foreground macro object) without requiring manual intervention, while achieving precise focus results.
3Measurement precision
If the imaging device uses phase detection autofocus with multiple focus perimeters, then focus values can be obtained and compared to identify macro objects, but the processing complexity increases
Solution Approach 1:
The patent applies local quality by assigning different weights or priorities to different focus perimeters based on their importance. The processor can identify which focus perimeter contains the most important subject (such as a foreground macro object) and prioritize that perimeter's focus metric in the final lens position determination. This allows the system to process multiple perimeters efficiently by focusing computational resources on the most critical depth zones rather than treating all perimeters equally, reducing overall processing complexity while maintaining high macro object detection accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures that macro objects are accurately focused, while also bringing nearby objects into focus, improving overall image clarity and reducing the likelihood of objects appearing out of focus due to mid-point focusing issues.
Implementation Method 1
Some electronic devices having cameras use phase detection autofocus for determining movement of the lens relative to the image sensor
Implementation Method 2
The lens may be moved towards or away from the image sensor to focus an object or scene onto the camera image sensor
Data Source
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Figure 4A~4C
AI summary
A method and device for autofocusing a macro object by an imaging device is provided. The imaging device includes a lens. In one aspect, the method includes: providing two or more focus perimeters in a viewfinder; obtaining a group of focus values, the group of focus values including at least one focus value associated with each of the two or more focus perimeters, each focus value in the group of focus values including a magnitude and a direction for causing movement of the lens; comparing focus values in the group of focus values to identify a macro object focus value; and in response to identifying the macro object focus value, determining autofocus settings based on the macro object focus value.