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1. (WO2017177465) CONTRAST DETECTION AUTOFOCUS USING ADAPTIVE STEP

Pub. No.:    WO/2017/177465    International Application No.:    PCT/CN2016/079506
Publication Date: Fri Oct 20 01:59:59 CEST 2017 International Filing Date: Sat Apr 16 01:59:59 CEST 2016
IPC: G03B 13/36
Applicants: SZ DJI TECHNOLOGY CO., LTD.
Inventors: YU, Lifu
Title: CONTRAST DETECTION AUTOFOCUS USING ADAPTIVE STEP
Abstract:
Systems, methods and/or devices are used for moving an optical device relative to an image sensor to focus an image. The image sensor acquires a first image. A first contrast variation rate is obtained. In accordance with a determination that the contrast variation rate meets a first threshold criterion, the optical device is moved by a first step size that is greater than a previous step size, to a second position. In accordance with a determination that the first contrast variation rate does not meet the first threshold criterion, the optical device is moved by a second step size that is smaller than the previous step size to the second position. The aforementioned operations are repeated until a second contrast variation rate determined for a second image that is acquired when the optical device is at the second position meets a second threshold criterion.