Camera Auto Focus Using Motion-Weighted Rolling Shutter Measures
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Solution Overview
Problem
Auto-focus systems in image capture devices, such as cameras in portable electronic devices, are slow and prone to producing blurry images due to camera movement, as they rely on trial and error to find the optimal lens position, which is delayed even when the camera is stable.
Innovation Solution
An auto-focus method for cameras with rolling shutter image sensors that continuously measures camera motion during image frame capture, dividing frames into focus windows and calculating weighted focus measures based on motion levels to account for pixel data read during movement, allowing for faster and more accurate focus setting even when the camera is in motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the auto-focus system uses trial and error to move the lens to find optimal focus position, then the focus can be achieved, but the process becomes slow and time-consuming
Solution Approach 1:
The patent applies preliminary action by continuously measuring camera motion levels during the rolling shutter readout process and using this motion data to weight focus measures before performing auto-focus calculations. This preliminary measurement and weighting of motion data allows the system to prepare focus information in advance, reducing the need for extensive trial-and-error lens movement and significantly speeding up the autofocus process while maintaining accuracy.
2Reliability
If the auto-focus system waits for image stability before processing, then blurry images are avoided, but the autofocus process is delayed
Solution Approach 1:
The patent converts the harmful effect of camera motion into a beneficial weighting factor. Instead of waiting for complete stability or discarding motion-affected data, the system measures the motion level during rolling shutter readout and uses this information to weight the focus measures accordingly. This allows the system to process images even during motion, converting what would normally be harmful motion-induced blur into useful motion-weighted focus information that speeds up autofocus while maintaining image quality.
3Productivity
If the camera is moving during auto-focus operation, then the subject becomes inconsistent, but the patent enables focus measurement by weighting pixel data based on motion levels
Solution Approach 1:
The patent applies local quality by assigning different weights to different pixel regions based on their individual motion levels during the rolling shutter readout. Each pixel region's focus measure is weighted according to the specific motion characteristics of that region, allowing the system to maintain measurement precision even when the camera is moving. This localized weighting approach enables productive autofocus operation during camera motion while preserving focus measurement accuracy.
Data Source
AI summary
The present invention relates generally to auto focus algorithms for setting a focus of a camera. More specifically, the present invention relates to a method (600) and device for setting a focus of a camera wherein a camera motion level of the camera is continuously measured (S604) during the read-out of pixel data by a rolling shutter image sensor and wherein the auto focus algorithm uses weighted focus measures which are calculated (S612) using the continuously measured camera motion levels.