CN102331652A - Real-time automatic focusing method - Google Patents

Abstract

The invention discloses a real-time automatic focusing method, which is suitable for a pick-up device. The real-time automatic focusing method comprises the following steps of: checking an environment in real time by using a focusing environment judging unit of a real-time automatic focusing system to decide whether to move a lens during the image accquiring process of a charge-coupled device (CCD); and comparing by computing contrast to decide the moving direction of the lens. According to the method, the aim of focusing in real time can be fulfilled; the lens can be finely adjusted to increase the focusing accuracy; and moreover, programs are optimized, and resources are saved.

Description

A kind of in real time automatic focusing method

Technical field

The present invention relates to camera head CCD acquisition technology field, particularly a kind of in real time automatic focusing method.

Background technology

Along with the fast development of automatic control technology and image processing techniques, Autofocus Technology is applied to a plurality of fields, such as industrial optical detection, medical image system, multimedia technology field etc.In commercial production, usually need carry out quality testing to exact instrument, distinct image information is obtained in this victory of will seeking quickness exactly.In this used, Autofocus Technology highlighted crucial effects.

General; Adopting the microscopical automatic focusing mode of image processing techniques is to present whole inverted image after reflexing to convex lens by natural light; Through the camera continuously shot images; And constantly compare and analyze, control moving lens repeatedly, up to finding out the most distinct image as the criterion of focus point.Yet great amount of images information need stored and handle to this automatic focusing mode, and influence is the speed of focusing automatically.

In addition, existing real-time autofocus system has following defective and deficiency in actual use:

(1) no matter whether the capture environment changes, set per 3 seconds usually and focus once automatically, therefore cause unnecessary power consumption.

When (2) focusing automatically, camera lens need be covered the focusing step number that sets, and just can find out best focus then, so focusing speed is slower, and can't reach the purpose of real " real-time focusing " at every turn.

(3) the focusing step number that sets according to camera lens of the degree of accuracy of existing focusing automatically what and decide; Under the situation of considering speed; Therefore usually can't set more focusing step number to camera lens, be difficult to camera lens is finely tuned, thereby have influence on the degree of accuracy of automatic focusing.

In sum, the weak point of the automatic focusing method existence of ccd image collection at present is: the purpose that does not reach real-time focusing; And be difficult to camera lens is finely tuned and then influenced the degree of accuracy of focusing; In addition, the focusing program design is unreasonable, causes unnecessary waste.

Summary of the invention

Technical matters to be solved by this invention provides a kind of in real time automatic focusing method, and this method can realize the purpose of focusing in real time; Thereby and can finely tune the degree of accuracy that improves focusing to camera lens; In addition, optimizer is saved resource.

For solving the problems of the technologies described above, the technical scheme that the present invention adopts is: a kind of in real time automatic focusing method is applicable in the camera head that the autofocus system of employing comprises focusing environment judging unit, comprises the following steps:

Whether

is changed by the focusing environment judgment unit judges focusing environment of real-time autofocus system;

if yes; Then enabling counting device, and setting N=0; If not, CCD images acquired again then;

calculates correlative value by the resulting picture of CCD again;

then equals (N+1) by this counter records cycle index;

judges that then whether this cycle index is greater than the global cycle number of times of being scheduled to;

be not if; Then by the resulting picture of CCD, to calculate another correlative value; If yes, the step restarts then to get back to

;

does comparison with this another correlative value and previous correlative value, to judge that whether this another correlative value is greater than previous correlative value;

if yes, then drive unit drives camera lens and moves down; If, then drive unit driving camera lens does not move up;

is by this cycle index of counter records;

The circulation of

repeating step

~

, up to this cycle index greater than the global cycle number of times of being scheduled to.

Preferably, said focusing environment judging unit comprises automatic exposure unit and AWB unit.

Preferably,

said drive unit comprises motor and the piezo-electric device that is attached thereto in the step.

The present invention has following beneficial effect with respect to prior art:

1, the in real time automatic focusing method of the present invention is to order about camera lens according to the resulting image information of CCD to move toward correct direction, and focusing speed is fast, in real time focusing;

2, the present invention in real time automatically the focusing method through constantly camera lens being finely tuned, thereby increase the accuracy of focusing;

3, the in real time automatic focusing method of the present invention has been optimized the focusing program, compares with prior mechanical focusing method, and flexible movements reduce unnecessary waste simultaneously.

Description of drawings

Fig. 1 is the process flow diagram of the in real time automatic focusing method of the present invention.

Embodiment

Below in conjunction with embodiment and accompanying drawing the present invention is described in further detail, but embodiment of the present invention is not limited thereto.

As shown in Figure 1; A kind of in real time automatic focusing method; Be applicable in the camera head that this in real time automatic focusing method is in CCD images acquired process, the focusing environment judging unit real-time inspection environment through real-time autofocus system determines whether moving lens earlier; Again through calculating contrast and carrying out the moving direction that camera lens is relatively decided in front and back.The autofocus system that adopts comprises focusing environment judging unit, and this focusing environment judging unit comprises automatic exposure unit, AWB unit and other judgment means.

This method comprises the following steps:

Whether is changed by the focusing environment judgment unit judges focusing environment of real-time autofocus system;

if yes; Then enabling counting device, and setting N=0; If not, CCD images acquired again then;

calculates correlative value by the resulting picture of CCD again;

then equals (N+1) by this counter records cycle index;

judges that then whether this cycle index is greater than the global cycle number of times of being scheduled to;

be not if; Then by the resulting picture of CCD, to calculate another correlative value; If yes, the step restarts then to get back to

;

does comparison with this another correlative value and previous correlative value, to judge that whether this another correlative value is greater than previous correlative value;

if yes, then drive unit drives camera lens and moves down; If, then drive unit driving camera lens does not move up; Wherein, this drive unit comprises motor and the piezo-electric device that is attached thereto;

is by this cycle index of counter records;

The circulation of repeating step

~

, up to this cycle index greater than the global cycle number of times of being scheduled to.

The foregoing description is merely preferred embodiment of the present invention, is not to be used for limiting practical range of the present invention.Be that all equalizations of doing according to content of the present invention change and modification, all contained by claim of the present invention scope required for protection.

Claims (3)

1. real-time automatically focusing method, the autofocus system of employing comprises focusing environment judging unit, it is characterized in that, comprises the following steps:

Whether is changed by the focusing environment judgment unit judges focusing environment of real-time autofocus system;

if yes; Then enabling counting device, and setting N=0; If not, CCD images acquired again then;

calculates correlative value by the resulting picture of CCD again;

then equals (N+1) by this counter records cycle index;

judges that then whether this cycle index is greater than the global cycle number of times of being scheduled to;

be not if; Then by the resulting picture of CCD, to calculate another correlative value; If yes, the step restarts then to get back to ;

does comparison with this another correlative value and previous correlative value, to judge that whether this another correlative value is greater than previous correlative value;

if yes, then drive unit drives camera lens and moves down; If, then drive unit driving camera lens does not move up;

is by this cycle index of counter records;

The circulation of

repeating step

~ , up to this cycle index greater than the global cycle number of times of being scheduled to.

2. in real time automatic focusing method according to claim 1, it is characterized in that: said focusing environment judging unit comprises automatic exposure unit and AWB unit.

3. in real time automatic focusing method according to claim 1, it is characterized in that:

said drive unit comprises motor and the piezo-electric device that is attached thereto in the step.