Autofocus Circuitry Using Optical Flow for Moving Objects
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Solution Overview
Problem
Conventional cameras struggle to autofocus on a desired object among multiple moving objects within a field-of-view, often focusing incorrectly when the object of interest is not at the center and requires manual user input to adjust lens settings, which is cumbersome and difficult to maintain, especially when the object of interest changes frequently.
Innovation Solution
An electronic device equipped with an image sensor and circuitry that captures a sequence of image frames, detects prominent regions with optical flow similar to its own motion, selects a region-of-interest based on user focus tendencies, and estimates an autofocus point by computing the center of mass of the object-of-interest, automatically controlling the focus to minimize deviation from the initialized position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional camera autofocuses on center portion of field-of-view, then autofocus function is simple to implement, but it cannot correctly focus on objects located away from center
Solution Approach 1:
The system performs preliminary actions by detecting prominent regions and computing their motion vectors before determining the final autofocus point. This preliminary analysis of multiple candidate regions and their motion characteristics enables accurate focus selection without requiring complex real-time processing during capture
Solution Approach 2:
The patent introduces motion vectors as an intermediary element to bridge the gap between simple center-based autofocus and accurate object-focused autofocus. By computing motion vectors for prominent regions and comparing them with the electronic device's motion vector, the system identifies objects of interest without requiring complex direct analysis
2Reliability
If manual lens adjustment is required to follow moving objects, then focus can be maintained on moving objects, but user operation becomes cumbersome and difficult to maintain
Solution Approach 1:
The electronic device performs self-service by automatically detecting prominent regions, computing their motion vectors, and determining autofocus points without requiring manual user intervention. The system autonomously tracks moving objects by comparing region motion vectors with its own motion vector, maintaining reliable focus on objects of interest
Solution Approach 2:
The system implements feedback by continuously analyzing motion vectors of prominent regions and comparing them with the electronic device's motion vector. This feedback mechanism enables automatic identification of objects of interest and dynamic adjustment of autofocus points to maintain reliable focus on moving objects
3Adaptability or versatility
If user must track and manually calibrate lens for different objects of interest, then focus can be maintained on changing objects, but it is difficult to keep track of different objects and calibrate lens dynamically
Solution Approach 1:
The system performs preliminary detection of prominent regions and computation of their motion vectors before determining which object becomes the new object of interest. This preliminary analysis enables seamless transition between different objects without requiring complex real-time lens calibration when objects change
Solution Approach 2:
The electronic device automatically adapts to different objects of interest by detecting prominent regions, analyzing their motion characteristics, and determining autofocus points without requiring manual lens calibration. The system self-adjusts when objects change by identifying new prominent regions with motion vectors matching the device's motion
Data Source
AI summary
An electronic device to autofocus on an object-of-interest within a field-of-view of the electronic device, includes an image sensor and a circuitry. The image sensor captures a sequence of image frames that includes a current frame and detect at least one prominent region in the current frame. The detected at least one prominent region has an optical flow similar to a direction of motion of the electronic device. The circuitry selects a region-of-interest from the detected at least one prominent region and estimates an autofocus point in the detected at least one prominent region. The circuitry controls focus of the image sensor at the estimated autofocus point in the current frame. The focus of the image sensor is controlled such that the estimated autofocus point exhibits a minimum deviation from an initialized position for the estimated autofocus point within the detected at least one prominent region.