Chromatic DFD Autofocus for Faster Lens Positioning
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Solution Overview
Problem
Existing depth from defocus (DFD) techniques consume excessive power and cause lens wobbling due to repeated movement of the actuator and require multiple image captures, leading to reduced focus speed.
Innovation Solution
An electronic device adjusts focus based on the spread level of a display object using chromatic DFD techniques, minimizing unnecessary lens movements by estimating the on-focus position more accurately and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DFD technique uses repeated image capture at two positions to estimate distance and adjust focus, then the focus adjustment can be performed, but a large amount of power is unnecessarily consumed due to repeated actuator movement
Solution Approach 1:
The system performs preliminary focus estimation using the first image at the first position before actually moving the lens. By calculating the on-focus position based on spread level differences in the first image alone, the system avoids unnecessary repeated actuator movements and reduces power consumption while maintaining focus adjustment accuracy.
2Reliability
If images are taken at two positions and the lens position is moved to the on-focus position, then focus adjustment is achieved, but the lens position is repeatedly moved around the on-focus position causing wobbling
Solution Approach 1:
The system calculates the on-focus position in advance using image analysis before physical lens movement occurs. This preliminary calculation allows the lens to be moved directly to the correct position without repeated adjustments, eliminating wobbling and stabilizing the lens position while maintaining focus accuracy.
3Measurement precision
If two or more images must always be obtained for focus estimation, then the focus can be determined, but the speed of finding on-focus is lowered
Solution Approach 1:
The system extracts sufficient focus estimation information from a single first image by analyzing spread level differences between color channels. This eliminates the need to capture and process multiple images, significantly increasing focus speed while maintaining measurement precision through the extracted chromatic aberration data.
4Ease of operation
If the lens is moved to the on-focus position based on repeated image analysis, then focus is adjusted, but unnecessary lens movements consume excessive power
Solution Approach 1:
The system replaces repeated mechanical image capture and analysis with a single image-based computational method. By using spread level difference analysis on one image to determine the on-focus position, the system eliminates unnecessary actuator movements and associated energy losses while maintaining full focus adjustment capability.
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
The method improves focus speed and prevents lens wobbling while significantly reducing power consumption by optimizing focus adjustments.
Implementation Method 1
an image sensor, and a processor. The processor obtains a first image of a display object by using the image sensor
Implementation Method 2
a lens assembly including one or more lenses
Data Source
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AI summary
An electronic device is provided. The electronic device includes a processor configured to obtain a first image of an external object, generate a first color image and a second color image by using the first image, identify a difference in first spread level between a display object of the first color image and the display object of the second color image, determine a first on-focus position of a lens w based on the difference in first spread level, move the lens in a direction corresponding to the first on-focus position, obtain a second image of the external object, determine a second on-focus position of the lens based on a difference in second spread level between the external object contained in the first image and the external object contained in the second image, and move the lens to the second on-focus position.