CN1790095A - Automatic image focusing system and method - Google Patents

Abstract

The invention discloses an image self-focusing method and realization system, which comprises the following steps: providing user end computer with machine measurement and focusing control function for the detected object; supplying charge coupler and industrial optical lens to gather the continual image due to measuring the Z axle of machine; providing the image acquisition card to gain the continual image; supplying the control card to send order for controlling the Z axle motor to move within the named scale; sending the focusing order to the initiating system; obtaining the image of charge coupler; predisposing the obtained image; calculating the present image articulation; judging whether the Z axle reaches in the focusing scale or second focusing; calculating the focal point according to the articulation; driving Z axle motor to reach and output the position of focal point.

Description

Image autofocus system and method

【Technical field】

The present invention relates to an image measurement system and method, in particular to a system and method for auto-focusing during image measurement.

【Background technique】

Office Automation (OA) is indispensable in the current information-based society. In addition to using computers to process and store large amounts of data, optical scanners (Scanners) are used as documents, forms and images. The input device is widely used because it can effectively improve the efficiency of data input processing, and has become one of the standard equipment of computers.

When the existing optical scanners scan the originals of different sizes, it is achieved by switching a group of multi-lens mechanisms. When different sizes are switched to lenses with different magnifications to correspond to them, the focal length can be projected on the charge-coupled device. (Charged Coupled Device, CCD). Although these lenses adopt the same total optical path, and are arranged on the multi-lens mechanism in the mode of a relevant matching position, so that it can be correctly imaged on the charge-coupled device, yet, because the lens is a compound lens, it cannot There will inevitably be a small error in the process, and the total optical path and focal length required for clear imaging of each lens may be slightly different. Therefore, in the process of lens switching, its image cannot be accurately imaged on the charge-coupled device, and even if the optical scanner has only one lens, the accuracy of lens focus imaging is often affected by lens processing or installation errors .

The China State Intellectual Property Office authorized the announcement on May 26, 1999 with the announcement number CN2321022Y and the patent titled "autofocus device". This patent provides an autofocus device that is installed on an optical scanning machine. The device includes A lens positioning adjustment unit capable of adjusting the position of the lens, a CCD positioning adjustment unit capable of adjusting the position of a charge-coupled device (CCD), and a control unit capable of controlling the actions of the lens positioning adjustment unit and the CCD positioning adjustment unit. When the scanner is turned on, it can automatically adjust the optical path and focal length required for lens imaging, and move the lens and charge-coupled device to an appropriate position, so that the lens can accurately focus and image the target on the charge-coupled device , so that the resolution of the optical scanning machine is greatly improved.

However, the above-mentioned invention is only based on the adjustment of hardware devices to achieve focusing, and does not meet the requirements of office automation. Therefore, it is necessary to propose a system and method that can use a software program embedded in a computer to perform image measurement on an object to be measured. The control is performed to achieve the automatic focusing function, so that the focusing device not only has a simple structure and low cost, but also can ensure focusing precision.

【Content of invention】

The object of the present invention is to provide an image auto-focus system.

Another object of the present invention is to provide an image auto-focus method.

The invention discloses an image auto-focus system, which includes an image measuring machine for placing an object to be measured and a client computer for image focusing. A charge-coupled device (CCD) is installed on the Z-axis of the measuring machine, and an industrial optical lens is installed in front of the CCD, and continuous images can be collected through the industrial optical lens and the CCD. The client computer includes an image capture card and a control card, the image capture card is connected to the CCD through the image data line, and is used to obtain continuous images collected by the CCD and the industrial optical lens; the control card passes through another The data line is connected to the Z-axis motor of the measuring machine, and is used to send control instructions to the Z-axis motor to drive the Z-axis motor to move in a designated area. The data line connecting the Z-axis motor and the control card is different from the data line connecting the image capture card and the CCD.

The client computer also includes the following functional modules: an input/output module, which is used to obtain the continuous images collected by the industrial optical lens and CCD through the image capture card to the client computer for analysis and processing, and output and drive the Z-axis motor through the control card The command to move back and forth in the designated area outputs the focus position on the interface of the client computer; a parameter setting module is used to set parameters, including setting the calculation area of the image, setting whether to filter, and setting the amount of calculation ; a calculation module, used to calculate the image definition and calculate the focal point through the height of the definition; a data temporary storage module, used to save the calculated definition value and the Z-axis position of the machine corresponding to the definition value; a judgment The module is used to judge whether the Z-axis has reached the set position and whether it is the second focus. If the Z-axis has not reached the set position, it will issue a command to drive the Z-axis motor to continue moving, and send the command to the Z-axis through the control card The motor makes it move. The calculation module calculates the sharpness according to the pixel value of the image, and the pixel value is processed by the gradient method, and the sharpness evaluation function is the sum evaluation function of the absolute value of the gray scale in the four fields.

The present invention also discloses an image autofocus method, which includes the following steps: (a) providing a measuring machine for placing the object to be measured and a client computer for controlling focusing; (b) providing a Z-axis motor on the measuring machine A charge-coupled device (CCD) and an industrial optical lens are used to collect continuous images of the object to be measured; (c) an image capture card is provided in the client computer to obtain the above-mentioned continuous images; (d) a continuous image is provided in the client computer The control card is used to send commands to control the Z-axis motor to move within the specified range; (e) to send focus commands to initialize the system; (f) the image capture card to obtain continuous images output by the CCD; (g) to preprocess the above-mentioned obtained continuous images Image; (h) calculate the sharpness of the current image according to the pixel value of the image and the sharpness evaluation function; (i) judge whether the Z axis reaches the set position, that is, the focus range, if the Z axis does not reach the set position, then drive the Z The axis continues to move, acquire the current image and return to step g; (j) judge whether it is the second focus, if it is not the second focus, re-designate the starting position according to the level of definition, and drive the Z-axis back to the above-mentioned re-designated The starting position continues to move, and returns to step g; (k) calculates the focus according to the level of definition, and drives the Z-axis motor to reach the focus position; (l) outputs the focus position, and ends focusing.

The preprocessing includes clearing the temporary data calculated last time and filtering image impurities.

The present invention determines a search interval by controlling the measuring machine, moves the Z axis of the machine up and down, collects continuous images by using the industrial optical lens and CCD, and dynamically analyzes the images at the same time, finally calculates the focus position, and moves The Z axis moves to the focus position to get a clear image. The invention has simple structure, low cost and can ensure precision.

【Description of drawings】

FIG. 1 is a hardware architecture diagram of the image auto-focus system of the present invention.

Fig. 2 is a functional block diagram of the client computer of the present invention.

FIG. 3 is a flow chart of the image auto-focusing method of the present invention.

【Detailed ways】

At first, the term used in the present invention is explained as follows:

CCD: Charged Coupled Device, charge coupled device or charge coupled device.

Referring to FIG. 1 , it is a hardware architecture diagram of the image auto-focus system of the present invention. The image auto-focus system includes a client computer 11 and a machine 19 for placing objects. Wherein, there is also a device CCD16 for collecting continuous images on the Z axis of the machine platform 19. The CCD16 is equipped with an industrial optical lens 18, and the CCD16 focuses the image through the industrial optical lens 18. The client computer 11 is equipped with an image capture card 12 , a control card 13 and a data storage area 20 . Wherein CCD16 links to each other with described image capture card 12 through an image data line 14, and CCD16 transmits the video signal obtained from machine platform to image capture card 12 through this image data line 14; Described control card 13 passes another A different control signal data line 15 is connected to the Z-axis motor 17, and the control signal data line 15 transmits control instructions to drive the Z-axis motor 17 to move back and forth in a designated area; the data storage area 20 is used to save the calculated current image The sharpness value and the Z-axis position of the machine corresponding to the sharpness value.

Referring to FIG. 2 , it is a functional block diagram of the client computer of the present invention. The client computer 11 includes an input/output module 111 , a parameter setting module 112 , a calculation module 113 , a data temporary storage module 114 and a judgment module 115 . The input/output module 111 is used to acquire the continuous images collected by the industrial optical lens 18 and CCD through the image capture card 12, and transmit them to the client computer 11 for analysis and processing, and output through the control card 13 to drive the Z-axis motor to move back and forth in the designated area command and output the focus position on the interface of the client computer 11. The parameter setting module 112 sets parameters, including setting the calculation area of the image, setting whether to filter, and setting the calculation amount. The larger the calculation amount, the more accurate the calculated focus and the slower the speed; otherwise, the less accurate the focus , the faster the speed. The calculating module 113 is used for calculating the image definition and calculating the focus according to the level of the definition. The data temporary storage module 114 is used to store the calculated sharpness value and the Z-axis position of the machine corresponding to the sharpness value in the data storage area 20 . The judging module 115 is used for judging whether the Z-axis 17 has reached the set position and whether it is the second focus. If the Z-axis does not reach the set position, an instruction to drive the Z-axis motor 17 to continue moving is issued, and the control card 13 transmits the instruction. The Z-axis motor 17 is commanded to move.

Referring to FIG. 3 , it is a flow chart of the image auto-focusing method of the present invention. First, a focus command is issued through the client computer 11 (step 300). Initialize the focus system, that is, set some parameters and control the Z-axis of the machine to reach a position set by the user. This position is calculated by specifying an approximate position and the specified focus distance by the user. The set parameters refer to the set Calculation area of the image, setting whether to filter and setting calculation amount, etc., wherein the larger the calculation amount, the more accurate the calculated focus and the slower the speed; otherwise, the less accurate the focus, the faster the speed (step S302). Drive the Z-axis motor 17 to move back and forth in the designated area, CCD16 and industrial optical lens 18 collect the continuous images moved by the Z-axis motor 17, and the input/output module 111 transmits the digital image telecommunications of the continuous images transmitted by the CCD16 through the image capture card 12 The number is input into the client computer 11 (step S304). The client computer 11 performs pre-processing on the acquired image, the pre-processing is mainly to clear the temporary data calculated last time and filter image impurities (step S306). The sharpness of the current image is calculated according to the pixel value of the image. The pixel value is processed by the gradient method, that is, the larger the gradient value of two adjacent pixels, the sharper the image, and the more obvious the difference between black and white pixels. The sharpness evaluation used The function is the sum evaluation function of the absolute value of the gray difference in the 4 fields, as shown below:

$\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span>$

And store the calculated sharpness value and the machine Z-axis position corresponding to the value in the data storage area 20 (step S308). Determine whether the Z-axis has reached the set position. The set position refers to the range of focus (a maximum value and a minimum value). The moving range of the Z-axis is 0-150 (mm). Generally, the focus range is set to 1- 2 (mm) (step S310). If the set position is not reached, the Z-axis of the drive machine continues to move, and at the same time, the image is acquired again and returns to step S306, and the calculation is performed again; if the set position is reached, then it is judged whether it is the second focus (step S312), If it is not the second time of focusing, redesignate the starting position according to the level of definition and drive the Z-axis of the machine back to the starting position, return to step S306 to recalculate and obtain the image and perform calculation again; The focus is calculated according to the height of the degree, and the Z axis is driven to reach the focus position at the same time (step S314). After the focusing is completed, the user terminal computer 11 outputs the focus position (step S316).

Claims (10)

1. image autofocus system, it comprises the user end computer that an image measuring machine and of placing object to be measured carries out the image focusing, it is characterized in that:

One charge-coupled device (CCD) is installed on the described measurement platform Z axle, and an industrial optical lens is adorned in this CCD the place ahead, can gather continuous image by industrial optical lens and CCD;

Described user end computer comprises a Frame Grabber and a control card, described Frame Grabber links to each other with CCD by the image data line, be used to obtain the continuous image of CCD and industrial optical lens collection, described control card links to each other with measurement board Z axle motor by another data line, be used for to Z axle motor sending controling instruction, move in the appointed area to drive Z axle motor.

2. image autofocus system as claimed in claim 1 is characterized in that, described connection Z axle motor is different from the data line that is connected Frame Grabber and CCD with the data line of control card.

3. image autofocus system as claimed in claim 1 is characterized in that, described user end computer comprises following functional module:

One input/output module, be used for obtaining continuous image to the user end computer that industrial optical lens and CCD gather and carry out analyzing and processing by Frame Grabber, drive the instruction that Z axle motor moves around in the appointed area by control card output, the focal position is exported on the interface of user end computer;

One parameter setting module is used for setup parameter, comprise the zoning of setting image, set whether to filter, the set-up and calculated amount;

One computing module, the height that is used to calculate image definition and pass through sharpness calculates focus;

The interim storage module of one data is used to preserve the board Z shaft position of the definition values that calculates and this definition values correspondence;

One judge module is used to judge whether the Z axle arrives desired location and judge whether to focusing for the second time, if the Z axle does not arrive desired location, then sends and drives Z axle motor and continue the instruction of moving, and transmits this instruction by control card and moves it to Z axle motor.

4. image autofocus system as claimed in claim 3, it is characterized in that, described computing module is according to the calculated for pixel values sharpness of image, and wherein the disposal route of pixel value is to adopt gradient method, and sharpness evaluation function is 4 field gray scale absolute value sum evaluation functions.

5. one kind is utilized the described system of claim 1 to carry out the image method of focusing automatically, it is characterized in that this method comprises the steps:

Send the focusing order, with initialization system;

Frame Grabber obtains the continuous image of CCD output;

The above-mentioned continuous image that obtains of pre-service;

The sharpness of calculating current image according to the pixel value and the sharpness evaluation function of image;

Judge whether the Z axle arrives desired location, i.e. focusing range;

Judge whether to be focusing for the second time;

Height by sharpness calculates focus, and drives Z axle motor arrival focal position;

Focusing is finished in the output focal position.

6. the image as claimed in claim 5 method of focusing automatically is characterized in that wherein the step initialization system also comprises the steps:

Set the zoning of image;

Whether set needs to filter;

The set-up and calculated amount;

Drive board Z axle and arrive initial position.

7. the image as claimed in claim 6 method of focusing automatically is characterized in that, described initial position is meant that driving the Z axle arrives predefined position, and this position is to specify the focusing of a Position Approximate and appointment from calculating by the user.

8. the image as claimed in claim 5 method of focusing automatically is characterized in that wherein the step of the above-mentioned continuous image that obtains of pre-service comprises:

Empty the last ephemeral data that calculates;

Filtering image impurity.

9. the image as claimed in claim 5 method of focusing automatically is characterized in that judge wherein whether the Z axle arrives desired location and also comprise step:

If the Z axle does not arrive desired location, then drive the Z axle and continue to move, obtain current image, and continue to handle the image that obtains again.

10. the image as claimed in claim 9 method of focusing automatically is characterized in that, wherein judges whether also to comprise step for focusing for the second time:

If not focusing for the second time, then reassign the starting position by the height of sharpness;

Driving Z axle is got back to above-mentioned starting position of reassigning and is continued to move;

Again obtain image and carry out focusing process.