A focusing method and device

Abstract

The focusing method and device provided by the embodiments of the present invention belong to the technical field of video surveillance. The method includes: acquiring a preliminary focus area according to the obtained focus point sharpness values ​​of images collected by the image acquisition device at multiple detection positions; The change state of focus point sharpness value of the focus area and the next preliminary focus area until the focus point sharpness value change state of the acquired preliminary focus area is normal; according to the focus point sharpness value change state of the normal preliminary focus area Acquiring a standard focus position; controlling the image acquisition device to move to a detection position corresponding to the standard focus position. By judging whether the change state of the sharpness value of the focus point in the pre-focus area is normal, it is possible to avoid falling into a local extremum, and reduce the search steps of the standard focus position, greatly simplify the focusing process, and improve the focusing accuracy.

Description

technical field [0001] The present invention relates to the technical field of video monitoring, in particular to a focusing method and device. Background technique [0002] The existing automatic focusing technology of digital image processing mostly obtains the image sharpness evaluation value through the sharpness evaluation function, and based on this value combined with some maximum sharpness evaluation value search algorithms, finds the maximum sharpness evaluation value, that is, obtains the sharpness evaluation value. Image. Usually, in a general focusing scene, as the focusing lens approaches or moves away from the actual focal point, the image sharpness increases or decreases correspondingly, and the sharpness evaluation curve of this scene presents a good single-peak type and the evaluation values ​​on both sides of the peak are monotonous decrease. The hill-climbing search algorithm for this scene combines the appropriate search step size and end conditions to ...

AI Technical Summary

Problems solved by technology

[0003] However, in scenes with moving objects or moving light sources, low-light or low-contrast scenes, the sharpness evaluation curve will have more false peaks compared to the single-peak type of general scenes, causing the focus search algorithm to fall into local extreme value, causing out-of-focus to appear

In this case, relying only on the focus evaluation value to search for a clear focus point, it is easy to search for a local extremum or cause the focus effect to vibrate repeatedly, affecting the accuracy of the focus effect

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