Automatic focusing method and image collecting device

Abstract

The invention discloses an automatic focusing method and an image acquisition device, wherein the device comprises at least one imaging lens, at least one focusing lens, a photosensitive device and a focal length regulation mechanism. The method comprises the following steps that: A. according to the actual scale of an object, the actual scale of an image formed on the photosensitive device by the object and the distance between the photosensitive device and the imaging lens, the product of the distance between the photosensitive device and the imaging lens and the actual object scale divided by the sum of the actual object scale and the actual image scale equals a focusing focal length estimation value FF; B. the focal length regulation mechanism is regulated to allow the focal length to reach the focusing focal length estimation value FF; C. the focal length is fine-adjusted to a plurality of focal length positions around the focusing focal length estimation value FF; the focusing estimation value of the image formed on each focal length position is calculated, and the focal length corresponding to the maximum focusing estimation value is taken as an accurate focusing focal length MF; D. the focal length regulation mechanism is regulated to allow the focal length to reach the accurate focusing focal length MF, and then the automatic focusing process is accomplished.

Description

technical field [0001] The invention relates to an automatic focusing technology, in particular to an automatic focusing method and an image acquisition device based on face detection. Background technique [0002] For the image acquisition device, the distance between the object to be photographed and the acquisition device is often in a state of change. In order to capture a clear image, the focal length must be adjusted according to the distance of the object to be photographed relative to the acquisition device. This process of automatically adjusting the focus to obtain a clear image is called autofocus. [0003] The general focusing algorithm adopts all adjustable ranges of the focal length, collects images and analyzes them, obtains the evaluation value of the sharpness of each position, and calculates the focal length position corresponding to the maximum evaluation value, adjusts the focal length to this position, and Get a sharp image. [0004] Generally speaking...

AI Technical Summary

Problems solved by technology

[0004] Generally speaking, the adjustment range of the focal length of the lens is relatively wide, and the focal length adjustment mechanism is a mechanical device, which requires a long time for image acquisition and analysis for all positions, especially for fast-changing objects, the focusing process is too cumbersome

[0005] In summary, the existing autofocus technology obviously has inconvenience and defects in actual use, so it is necessary to improve it

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