Automatic focusing method, lens module and imaging device

Abstract

Automatic focusing method comprises: controlling lens to move stepwise along preset direction from initial scanning position with first step size, calculating first contrast; determining whether meeting first preset condition; arranging fine-scan position according to determination result; controlling lens to move stepwise along reverse direction of preset direction from fine-scan position with second step size, calculating second contrast of imaging region corresponding to each lens position; determining whether meeting second preset condition; if so, designating lens position corresponding to second contrast as target imaging position. By calculating first contrast and determining, it can determine quickly range of imaging focal length, by calculating second contrast and determining, it can determine target imaging position quickly. Since not all lens positions have to be traversed, and step size is adjustable, not only reduce focusing time consumption effectively, but adapt to all kinds of scenes, problem of how to achieve high-efficient automatic focusing is solved

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