Automatic focusing method for digital image pickup device

Abstract

The auto focusing method for a digital image acquisition device comprises: A. selecting the initial movement direction for lens, let it move to a position; let r = 0 and s = 1; B. calculating and recording corresponding boundary information of current lens position; C. deciding whether it has found out the maximal value of information value; if yes, determining current lens position as the accurate focus position, the process ends; D. if meeting lens deflecting condition, let lens movement direction as the inverse one for current movement, let s = 0 and r = r+1; E. if r>1, taking lens position with known maximal boundary information value as the focusing position, the process ends; F. moving lens along preset direction, let s = s+1, and turning to step B.

Description

technical field [0001] The invention relates to an automatic focusing method of an image capture device, in particular to an automatic focus method of a digital image capture device. Background technique [0002] A patent document whose publication number is CN1794032 discloses an autofocus method, comprising the following steps: a) acquiring the image data of the initial position of the lens and extracting the edge of the image, counting the pixel values ​​of each point on the edge to obtain the boundary and store the information value, and store the corresponding lens position at the same time; b) move the lens, and obtain the boundary information value of the image corresponding to the current lens position according to the method described in step a); c) compare the boundary information value of the current image with the above For the boundary information values ​​stored once, save the larger value and its corresponding lens position, and then perform steps b) and c) in...

AI Technical Summary

Problems solved by technology

[0009] However, this method is only applicable in an ideal state, that is, only when there is only one peak in the boundary information value curve, that is, when the left side of the peak rises monotonously and the right side monotonically decreases, the maximum value of the boundary information value can be accurately found

However, in the actual application environment, the curve of the boundary information value fluctuates, that is, there are multiple peaks in the curve of the boundary information value. In this case, the method often cannot accurately locate the maximum value of the boundary information value, and cannot accurately focus

Images