CN101813946B - Automatic object distance adjusting method and device of imaging system - Google Patents

Abstract

The invention relates to automatic object distance adjusting method and device of an imaging system. The device comprises a computer respectively connected with a control unit and a CCD (Charge Coupled Device) camera; the control unit is connected with a driving mechanism and used for receiving a control command sent from the computer, executing the command on the driving mechanism and then reporting to the computer that the object distance adjustment is completed; a measured object is put on a measured object tray; the measured object and the measured object tray are located within the shooting area of the CCD camera; the driving mechanism is connected with the measured object tray and is used for completing a transmission function of the driving mechanism from a motor to the measured object tray; the computer comprises an image segmentation processor, a computation processor and a data storage, wherein the image segmentation processor is used for segmenting an area of the tray, occupied by the measured object; the computation processor is used for computing the size of a visual area and the object distance; and the data storage is used for storing a two-dimensional data table and prior knowledge threshold values and updating the two-dimensional data table and the prior knowledge threshold values. The invention has convenient and accurate object distance adjustment and greatly reduces the object distance adjusting time in imaging of the measured object.

Description

Method and device for automatic adjustment of object distance in imaging system

technical field

The present invention relates to the field of optical imaging technology, image segmentation processing and automatic control technology, in particular to the positioning calculation of optical camera imaging, the basic segmentation processing of images and automatic control system technology and the imaging device realized by the above technology to make the object distance automatic Adjust to a technical field where the image is clear and the viewing area is accurate.

Background technique

In the traditional imaging system for obtaining intermediate information of small animals, adjusting the object distance to change the field of view is done manually, and the clarity of the camera imaging is observed while manually adjusting until it is suitable; currently the US caliper life sciences The company's IVIS system uses four specific positions to image a mouse's head, one mouse, three mice, or five mice. See http://www.brainshark.com/brainshark/vu/view.asp? text＝Website&pi＝169421910&uid＝0&sid＝31771436&sky＝879491595FF0481789681DE6A5A11D68 Retrieved on 2008-11-17. This method cannot adapt to the needs of measured objects of different sizes. When the size of the measured objects is very different, the fixed four positions may not be able to meet the accurate selection of the visible area. When the area of interest occupies a large part of the visible area When it is a small part, the utilization efficiency of the CCD will be relatively low, and the signal-to-noise ratio of the image will also decrease accordingly. Therefore, this system is strictly limited by the size of the measured object. The viewing area of the NightOWL LB 981 NC 100system from Berthold Technologies in Germany is only 20cm×20cm, which can image four mice at the same time, see the application note Luciferin bioavailability in mice during in-vivoimaging on page 3 and 4 pages, the download link is http://www.bertholdtech.com/ww/en/pub/bioanalytik/bioprodgroup/overview/applications/notes.cfm Retrieved on 2008-11-17. In addition, adjusting the object distance for a long time by manual or human observation to obtain a clear image and an ideal viewing area will be limited by the reaction time of the chemical reagents in the object being studied and the anesthesia depth of the anesthetic. Obviously, it is difficult to guarantee the artificial adjustment time, and several fields of view at fixed positions cannot satisfy the best imaging effect of different sizes of measured objects. When the area occupied by the measured object occupies a small part of the visible area, pay attention The regional resolution of the part is very low; when the visible area is only a part of the measured object, it is likely to miss useful information on other parts of the measured object.

Contents of the invention

In order to solve the problems in the prior art, the object of the present invention is to provide a method and device for automatically adjusting the object distance of an imaging system.

In order to achieve the above object, the present invention provides a method for automatically adjusting the object distance of an imaging system, comprising the following steps:

Step 1: Set a two-dimensional data table corresponding to the object distance and the square visible area within the adjustment range of the object distance of the imaging system. 10% to 20% of the change in side length is used as the minimum division of the object distance.

Step 2: Select a specific location with a known far-field area and a corresponding known object distance;

Step 3: Imaging the tray of the object under test and the shape of the object under test at the specific position;

Step 4: Segment the object shape image to obtain the number of pixels of the square side length of the area occupied by the measured object, and calculate the square side length of the area occupied by the measured object on the image with reference to the known CCD camera pixel side length size;

Step 5: According to the known object distance, the focal length of the CCD camera lens and the optical imaging theory, the image distance and image reduction factor are obtained, and the actual square side length of the area occupied by the measured object on the image and the image reduction factor are used to calculate the actual The side length of the square area occupied by the measured object on the measured object tray;

Step 6: Check the calculated object distance corresponding to the visible area of the actual measured object in the two-dimensional data table, and move the measured object tray to the position of the object distance, in order to ensure that the measured object is completely visible Inside the area, set the object distance as the calculated object distance plus a margin of 1% to 5% of the calculated object distance.

In order to achieve the above object, the present invention provides a device for automatic adjustment of the object distance of the imaging system, which includes:

The computer is connected with the control unit and the CCD camera respectively; the control unit is connected with the drive mechanism 4, and the control unit is used to receive the control instructions sent by the computer, execute the instructions to the drive mechanism 4 according to the instructions, and report the completion of the computer object distance adjustment after completing the instructions; The measured object is placed on the measured object tray; the measured object tray and the measured object are located in the imaging area of the CCD camera; the driving mechanism 4 is connected with the measured object tray 5, which is used to complete the motor of the driving mechanism 4 to the measured object tray 5 transmission functions.

Beneficial effects of the present invention: the method and device of the present invention can adjust the optimal object distance more quickly, obtain a clear image and the region of interest is completely filled with CCD; improve the resolution and signal-to-noise ratio of the imaging image of the observed part; save The time for object distance adjustment in the experiment. The invention can quickly and automatically adjust the object distance between the maximum visible area and the minimum visible area, so that the size of the area occupied by the measured object can be automatically obtained, and the clearest imaging position can be calculated, and the object distance can be automatically adjusted at the same time. Image the object under test. After the shape imaging of the measured object is completed, the fluorescent area can be imaged and the size of the fluorescent emitting part can be obtained, and the object distance can also be adjusted twice to image the fluorescent area alone.

Other features and advantages of the present invention will become apparent from the following description of preferred embodiments, taken in conjunction with the accompanying drawings, to explain the principles of the invention by way of example.

Description of drawings

Fig. 1 is a flow chart of the working process of the method and device for automatically adjusting the object distance of the imaging system according to the present invention.

FIG. 2 is a structural schematic diagram of the automatic adjustment device for the object distance of the imaging system of the present invention.

Figure 3 is a block diagram of the internal structure of the control unit.

Fig. 4 The corresponding modules of the block diagram of image segmentation processing and object distance calculation in the computer.

Fig. 5 is a motor drive circuit diagram in the control unit.

Figure 6 is a schematic diagram of different object distances and fields of view.

Fig. 7 is a schematic diagram of segmentation detection.

Detailed ways

Various details involved in the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be pointed out that the described embodiments are only intended to facilitate the understanding of the present invention, rather than limiting it in any way.

FIG. 1 is a flow chart of the method for automatically adjusting the object distance of the imaging system according to the present invention and FIG. 2 is a schematic structural diagram of the device for automatically adjusting the object distance of the imaging system according to the present invention. Its method steps include:

Step 101: Set a two-dimensional data table corresponding to the object distance and the square visible area within the adjustable range of the imaging system object distance. The generation of the two-dimensional data table is to correspond different object distances to unique and different visual area, and the scale interval of the object distance can be determined according to the difference in size of different measured objects 6; here, 10% or 20% of the minimum side length variation of the measured object 6 is selected to determine. If the difference in the minimum side length of the measured object is 10mm, you can choose the division of the object distance as 1mm or 2mm.

Step 102: Select a specific position of a known far-field area and a known object distance; the imaging selection of the known far-field area is to just see the object distance position of the entire measured object tray 5, and this object distance _D is used as The quantity is known and the measured object tray 5 is first moved to this position; an image of the measured object tray 5 and the measured object 6 is captured at this position.

Step 103: Imaging the outlines of the measured object tray 5 and the measured object 6 at the specific position where the object distance is _D0 . After the measured object 6 is placed on the measured object tray 5, the automatic control system (including the content shown in Figure 3) and the mechanical connection structure (the driving mechanism 4 and the motor-driven screw 41 in Figure 2) drive the measured object tray 5 Go to the specified object distance position D ₀ and take the first image I ₀ . The computer 1 performs basic segmentation processing on the image I ₀ and calculates according to the optical imaging technology to obtain the size L ₀ ×L ₀ of the area occupied by the measured object 6; for the noise points outside the segmented area, use the image For each pixel, the gray level difference of 8 adjacent pixels is statistically analyzed, and the processing of elimination and retention is performed.

According to the size of L ₀ ×L ₀ , the computer 1 can calculate the optimal object distance D ₁ and the size of the visible area L ₁ ×L ₁ .

The automatic control system drives the measured object tray 5 to move to the _D1 position. According to the requirement, the local area imaging of the same process can also be performed on the part of interest on the measured object 6 by adjusting the object distance.

Step 104: Segment the object shape image of the measured object 6 to obtain the number of pixels of the square side length of the area occupied by the measured object 6, and calculate the measured object on the image with reference to the known 2-pixel side length of the CCD camera 6 The size of the square side of the occupied area; when the image is segmented, the measured object tray 5 painted with black matte paint is used, and the pixel grayscale of the captured image is determined by the parameters of the CCD camera 2 and the appropriate exposure time of the shooting environment light. The priori knowledge is used to select the segmentation threshold; the noise points outside the 6 regions of the measured object are eliminated by statistical analysis of the gray level difference of 8 adjacent pixels of the pixel.

Step 105: According to the known object distance, the focal length of the lens 21 of the CCD camera 2 and the optical imaging theory, the image distance and the reduction factor of the image can be obtained, and the square side length of the area occupied by the measured object 6 on the image and the size of the image can be used. The reduction factor calculates the side length size of the square area occupied by the actual measured object 6 on the measured object tray 5; the calculation of the area size occupied by the actual measured object 6 is to utilize the optical imaging formula and the known object distance and the focal length to obtain the image distance and reduction factor, and then calculate the side length of the area occupied by the measured object 6 on the image according to the pixel side length of the CCD camera 2, and finally calculate the actual measured object 6 according to the reduction factor. The size of the occupied area on the object tray 5.

Step 106: Find the calculated object distance corresponding to the visible area of the actual measured object 6 in the two-dimensional data table, and move the measured object tray 5 to the position of the object distance, in order to ensure that the measured object 6 is completely Inside the viewable area, set the object distance as the calculated corresponding object distance plus a margin of 1% to 5% of the object distance.

Step 107: Judging whether to move to the designated location, if yes, execute step 108, if otherwise, execute step 102;

Step 108: then end.

In the development of the system, in order to save cost and use conveniently, the CCD camera 2 in the system is usually matched with a fixed-focus lens, the focal length is selected as 50mm, and the aperture is selected as a product with a large aperture, such as an aperture of 1 or 0.8, which can satisfy The faint fluorescence of the organism passes through the aperture as much as possible during the long exposure time. In the system design, a one-to-one corresponding two-dimensional data table should be obtained for the relationship between the stroke of the motor-driven screw 41 of the driving mechanism 4 and the visible area of the CCD camera 2 on the measured object tray 5 .

After the interval division is determined, the corresponding number of the distance and the size of the visible area is determined accordingly. In this embodiment, according to the experimental requirements, the maximum variation range of the object distance of the device is 400mm, and every 2mm variation corresponds to a visible area, that is, a total of 200 visible areas, and such accuracy can already meet the needs. The corresponding relationship is shown in FIG. 6 . In each device, the corresponding two-dimensional data table must first be written into the data memory 13 of the processing software of the computer 1 . The motor of the driving mechanism 4 drives the lead screw 41 to move within the maximum visible area and the minimum visible area, so that the position corresponding to each control command issued by the control unit 3 corresponds to a uniquely determined visible area. The process starts at step 101, the measured object 6 is put into the center of the measured object tray 5 of the collection camera obscura, and the door of the camera camera obscura is closed. According to step 102 in the flowchart, after the computer 1 issues an instruction to automatically adjust the object distance, the control unit 3 moves the object tray 5 to the far field position (the visible area at this time is the entire object tray 5, and the drive mechanism The motor-driven lead screw 41 of 4 is also the maximum stroke, and the object distance is D ₀ ). At this time, according to step 103, the outline image I ₀ of the measured object tray 5 and the measured object 6 is taken under the condition of turning on the lighting in the dark box, and the obtained image is processed by an image segmentation processor according to step 104 in the process. 11 Carry out threshold segmentation, the specific method is according to the CCD camera 2 used in the embodiment of the present invention to the measured object tray 5 of the black matt paint under the uniform light environment of the dark box, the pixel of imaging under the situation that the exposure time is 1 second The grayscale value is generally between 4000 and 6000, and the obtained image grayscale information when the measured object 6 is a mouse is between 10000 and 50000 (when the CCD camera 2 is a true 16-bit dynamic range), the image After I ₀ is scanned row by row and segmented according to the threshold value 8000, the obtained segmentation result is finally obtained by taking the largest area according to the outermost edge of the coordinates, and the square formed by taking the longest side is the area occupied by the measured object 6 area. And eliminate the isolated points on the tray 5 of the measured object, and use the method of counting the gray level difference of 8 adjacent pixels around the pixel to eliminate, and when 5 of the 8 adjacent pixel differences are greater than 6000, do the elimination process , otherwise it is considered as the area of the measured object 6 (here the selection of the threshold can be obtained and saved into the segmentation threshold data memory 13 through different batches of the measured object 6 characteristics). After the division, take the square formed by the longest side length of one or several measured objects 6 as the area occupied by the measured object 6, because all the shapes of the measured objects 6 can be seen in this area, as shown in Figure 6 shown. According to step 105 in the process, the size of the area of the object under test 6 can be calculated. The calculation method is based on the known object distance at the far field position and the visible area. The visible area is the maximum square size of the object under test tray 5 . According to the optical imaging formula:

$\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; u</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

The focal length f is known in the formula (1), and the object distance u is also known as D ₀ at this time. The image distance v can be obtained according to the formula (1), and the reduction factor n ₀ can be obtained by dividing the object distance u by the image distance v. According to the square image side length L _1V of the area occupied by the measured object 6 obtained by segmentation, the image side length L _1V is the number of pixels m occupied by the side length of the measured object 6 that is divided by multiplying the pixel side length a ₀ is obtained, that is, the image side length L _1V =m×a ₀ , as shown in formula (2). The actual side length L ₁ of the square area occupied by the measured object 6 is obtained by multiplying the side length L _1V of the image by the reduction factor n ₀ . At the same time, formula (3) can be used to do a verification, wherein L _0R is the actual side length of the measured object tray 5, and L _0V is the side length in the captured image under the far field situation; when using the actual side length of the measured object tray 5 When the difference between the size and its length in the far-field image and the size calculated by the reduction factor is within the allowable error range δ (determine the specific value according to the experimental debugging, in the embodiment of the present invention, δ is 2mm), then it is considered The calculated side length _L1 of the square area occupied by the measured object 6 is correct. This process is done automatically by a computer program.

L _1V ＝m×a ₀ (2)

|L _0R -L _0v ×n ₀ |≤δ (3)

According to the size L ₁ ×L ₁ of the area occupied by the measured object 6, the corresponding object distance D ₁ can be selected by querying the pre-set two-dimensional data table. In order to ensure that the area occupied by the measured object 6 is completely covered by Captured by the CCD camera 2, the object distance sent by the computer 1 to the control unit 3 is D ₁ +ΔD, where ΔD is the margin of the object distance, which can be selected from 1% to 5% of D ₁ , that is, 4mm to 20mm. In the embodiment, it is 5mm. At this time, according to step 106 in the flowchart, the control unit 3 drives the motor to move the object tray 5 to the position where the object distance is D ₁ +ΔD. The motor of the drive mechanism 4 is a stepping motor, which is adjusted by a DSP controller 32 outputting a variable pulse width modulation (PWM) signal in the process of starting, accelerating, decelerating and stopping. When the LED indicator light in the relay K1 in the motor drive circuit Fig. 5 is turned on, the measured object tray 5 starts to move, stops running when it reaches the designated position, and the indicator light is turned off; at the same time, a stop signal will be output to the DSP controller 32 , the DSP controller 32 sends the execution result through the USB communication interface 31. According to the flow process 107 in FIG. Signal. If it does not move to the specified position, it will re-execute the moving instruction process according to the flow chart.

FIG. 2 is a structural schematic diagram of the automatic adjustment device for the object distance of the imaging system of the present invention. The whole device is mainly composed of a computer 1, a CCD camera 2, a lens 21 of the CCD camera 2, a control unit 3, a driving mechanism 4, a motor-driven screw 41, a tray 5 for an object to be measured, and an object 6 to be measured. The computer 1 is connected to the control unit 3 and the CCD camera 2 respectively; the control unit 3 is connected to the drive mechanism 4, and the control unit 3 is used to receive the control instructions sent by the computer 1, execute the instructions to the drive mechanism 4 according to the instructions, and report to the computer after completing the instructions 1 The object distance adjustment is completed; the measured object 6 is placed on the measured object tray 5; the measured object tray 5 and the measured object 6 are located in the imaging area of the CCD camera 2; the driving mechanism 4 is connected with the measured object tray 5, and the In order to complete the transmission function from the motor of the drive mechanism 4 to the object tray 5, the drive mechanism 4 is a motor-driven screw 41 displacement mechanism powered by a stepping motor, which is used to push the object tray 5 to move upward or push The measured object tray 5 moves downward.

The modules in the computer 1 include: an image segmentation processor 11, a calculation processor 12 and a data storage 13, which are integrated into the software environment of the automatic adjustment device for object distance of the imaging system. The image segmentation processor 11 is used to segment the area occupied by the measured object 6 on the measured object tray 5. The image segmentation processor 11 uses a segmentation threshold with prior knowledge to segment the area occupied by the measured object tray 5. segment the measured object 6 regions, and judge the noise points on the measured object tray 5 by using the statistical difference of the adjacent regions of the pixel, and do corresponding retention or elimination; the calculation processor 12 completes the visual region and the calculation of object distance; the data memory 13 is used to store the two-dimensional data table and the prior knowledge threshold, and update the two-dimensional data table and the prior knowledge threshold. The data memory 13 is to write the two-dimensional data table corresponding to the required object distance and the visible area during device debugging, and the required priori segmentation threshold. The data memory 13 can update the stored data, and can also Add content that needs to be expanded. Described object distance and visible area calculation processor 12, utilize optical imaging formula and known object distance and focal length to obtain image distance and reduction factor, then calculate the measured image on the image according to the pixel side length of CCD camera 2 The side length of the area occupied by the object 6, and calculate the size of the area occupied by the actual measured object 6 on the measured object tray 5 according to the reduction factor, here the longest side length is taken as the square of the area occupied by the measured object 6 side length.

The control software on the computer 1 can send an automatic adjustment command to the control unit 3, and after the adjustment, the control software will display that the automatic adjustment of the object distance is successful, and imaging can be performed. Data transmission, gain adjustment and transmission rate setting can be performed between the computer 1 and the CCD camera 2 . The control unit 3 can extend the control function of the lens of the CCD camera 2. In the embodiment of the present invention, the lens focal length control is not added, but the motor drive adjustment of the shooting distance is added. But this part is not the key point of the present invention, so it will not be described in detail here.

FIG. 3 is a block diagram of the internal structure of the control unit 3 . It mainly includes a controller 32 , a USB communication interface 31 , a motor drive circuit 33 , and a power supply module 34 and other main components. The structural block diagram also shows the signal flow relationship of several constituent structures. Described control unit 3: have a core DSP controller 32; Have a USB communication interface 31 to be connected with core DSP controller 32, be used for realizing the communication with computer 1; Have motor drive circuit 33 to be connected with core DSP controller 32, Used for the core DSP controller 32 to issue control instructions to the motor through the motor drive circuit 33; the motor drive circuit 33 is a motor control circuit based on pulse width modulation; it has a power supply module and a USB communication interface 31, a core DSP controller 32 and a motor drive circuit 33 connections.

Fig. 4 is a processing block diagram of image segmentation and object distance calculation in the computer 1 of the imaging system object distance automatic adjustment device according to my invention. As shown in Fig. 4, reference numeral 11 represents an image segmentation processor, reference numeral 12 represents a calculation processor, and reference numeral 13 represents a data memory. The image segmentation processor 11 divides the measured object 6 and the measured object tray 5 according to the threshold value stored in advance in the data memory 13; the calculation processor 12 can calculate the The size of the object distance corresponding to the visible area of the actual measured object 6 can drive the motor to move the measured object tray 5 to a designated position. The generation of the two-dimensional data table is to correspond different object distances to unique and different visual areas, and the scale of the object distance is determined according to the difference in the size of different measured objects 6; here, the smallest side of the measured object 6 is selected. Long variation of 10% or 20% to determine. In this embodiment, the difference of the minimum side length of the measured object 6 is about 10mm, and then the graduation of the object distance can be selected as 1mm or 2mm; then the object distance corresponding to the visible area is found by searching the two-dimensional data table, and the measured The moving distance of the object tray 5 is the corresponding object distance plus a margin of 1% or 5% of the object distance.

FIG. 5 is a schematic structural diagram of the motor drive circuit 33 in the control unit 3 . The upper part is mainly the modulation circuit. N1 uses an analog switch to modulate the input DJ_PWM signal, and the obtained signal drives the motor after passing through the instrument amplifier N2 and the power amplifier. The relay K1 controls the running and stopping of the motor, and the control signal DJ_CON of the relay K1 sent by the DSP controller controls the electromagnetic coil of the relay through the triode. Experiments show that the control precision of the motor can meet the requirement that the displacement error is less than 1mm. The +2.5V and -2.5V and +15V and -15V power supplies required in FIG. 5 are provided by the power module 34 in FIG. 3 .

Figure 6 is a schematic diagram of different object distances and fields of view. From the analysis in Figure 1, we have already known the field of view areas corresponding to different object distances in Figure 6. From Figure 6, we can see that the object distance D ₀ corresponds to the visible area L ₀ ×L ₀ , and the object distance D ₁ corresponds to the visible area L ₁ ×L ₁ , and the object distance D _i corresponds to the visible area L _i ×L _i . Wherein i can be any certain number from 1 to 200.

Fig. 7 is a schematic diagram of segmentation detection. In the flow chart of FIG. 1 , the length L ₀ of the edge of the tray 5 of the measured object and the side length L ₁ of the square area occupied by the measured object 6 obtained by segmentation have been described in the far field, that is, the maximum object distance.

The above is only a specific implementation mode in the present invention, but the scope of protection of the present invention is not limited thereto. Anyone familiar with the technology can understand the conceivable transformation or replacement within the technical scope disclosed in the present invention. All should be covered within the scope of the present invention, therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (12)

1. the self-adjusting method of imaging system object distance is characterized in that, may further comprise the steps:

Step 1: object distance and square viewing area two-dimensional data table one to one is set in the setting range of imaging system object distance;

Step 2: the ad-hoc location of selecting a known far-field region and its corresponding known substance distance;

Step 3: the profile of testee pallet and testee is carried out imaging at this ad-hoc location;

Step 4: utilize this amplitude object outside drawing to look like to cut apart, obtain the pixel count of the square length of side in the shared zone of testee, calculate the square length of side size in the shared zone of testee on the image with reference to the known CCD camera pixel length of side;

Step 5:, utilize the minification of the square length of side size in the shared zone of testee on the image and image to calculate actual testee shared square area size dimension on the testee pallet according to the minification that the focal length and the optical imagery theory of known object distance, CCD camera lens obtains image distance and image;

Step 6: the object distance distance that in two-dimensional data table, checks in the actual testee viewing area correspondence that calculates, the testee pallet is moved on the position of this object distance, for guaranteeing testee, object distance is set adds 1% to 5% allowance of this calculating object distance for calculating object distance fully in inside, viewing area.

2. the self-adjusting method of imaging system object distance according to claim 1, it is characterized in that, the generation of described two-dimensional data table is the viewing area that different object distances is corresponding unique, different, and the calibration of object distance is determined according to the difference of different testee sizes; 10% to 20% the minimum calibration of selecting the minimum length of side of testee to change as object distance.

3. the self-adjusting method of imaging system object distance according to claim 1, it is characterized in that, the imaging of described known far-field region selects to see just the object distance position of whole testee pallet, and this object distance at first moves on this position as known quantity and with the testee pallet; On this position, catch the image of a testee pallet and testee.

4. the self-adjusting method of imaging system object distance according to claim 1, it is characterized in that, utilize testee pallet that lacquer has a black lusterless paint to choose the threshold value of cutting apart by the priori of the pixel grey scale of the time shutter IT image of CCD camera parameter and the decision of shooting environmental light again during image segmentation; Adopt the difference of 8 adjacent position pixel grey scales of pixel to carry out statistical study to the rejecting of the extra-regional noise spot of testee.

5. the self-adjusting method of imaging system object distance according to claim 1, it is characterized in that, the calculating of the shared area size of described actual testee, be to utilize Optical Formula and known object distance and focal length to obtain image distance and minification, calculate the length of side in the shared zone of testee on the image again according to the pixel length of side of CCD camera, calculate the size in actual testee shared zone on the testee pallet at last according to minification.

6. the self-adjusting device of imaging system object distance is characterized in that, comprising:

Computing machine is connected with the CCD camera with control module respectively;

Control module is connected with driving mechanism, and control module is used for the steering order that receiving computer is sent, and, finishes the adjustment of instruction back report computing machine object distance and finishes the driving mechanism execution command according to instruction;

On the testee pallet, place testee;

Testee pallet and testee are positioned at the camera watch region of CCD camera;

Driving mechanism is connected with the testee pallet, is used to finish the transmission agency of the motor of driving mechanism to the testee pallet.

7. the self-adjusting device of imaging system object distance according to claim 6 is characterized in that described computing machine comprises:

The image segmentation processor was used for testee the cutting apart of shared zone on pallet;

Computation processor is finished the calculating to viewing area and object distance;

Data-carrier store is used to store two-dimensional data table and priori threshold value, and two-dimensional data table and priori threshold value are upgraded.

8. the self-adjusting device of imaging system object distance according to claim 6 is characterized in that described control module:

Has a core controller;

Have a USB communication interface and be connected, be used for realizing communication with computing machine with core controller;

Have a motor-drive circuit and be connected, be used for core controller and motor sent steering order by motor-drive circuit with core controller; Motor-drive circuit is based on the circuit for controlling motor of width modulation;

Having power module is connected with USB communication interface, core controller and motor-drive circuit.

9. the self-adjusting device of imaging system object distance according to claim 6, it is characterized in that, described driving mechanism is to be the driving mechanism and the motor-driven leading screw of power with the stepper motor, is used to promote the testee pallet and moves up or promote the testee pallet and move down.

10. the self-adjusting device of imaging system object distance according to claim 7, it is characterized in that, described image segmentation processor is to utilize the segmentation threshold with priori, testee zone on the testee pallet is cut apart, utilize the statistical discrepancy of pixel adjacent area to judge to the noise spot on the testee pallet simultaneously, and do corresponding reservation or rejecting.

11. the self-adjusting device of imaging system object distance according to claim 7, it is characterized in that, described computation processor, be to utilize Optical Formula and known object distance and focal length to obtain image distance and minification, calculate the length of side in the shared zone of testee on the image again according to the pixel length of side of CCD camera, and calculate the size in actual testee shared zone on pallet according to minification, get the longest length of side here as the foursquare length of side in the shared zone of testee.

12. the self-adjusting device of imaging system object distance according to claim 7, it is characterized in that described data-carrier store is the corresponding two-dimensional data table of object distance and viewing area that writes needs during device debugging, and the priori segmentation threshold that needs, this data-carrier store can updated stored data, also can increase the content that needs expansion.

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