CN109361854A - A kind of video camera focus adjustment method, apparatus and system based on MTF - Google Patents
A kind of video camera focus adjustment method, apparatus and system based on MTF Download PDFInfo
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- CN109361854A CN109361854A CN201811241588.4A CN201811241588A CN109361854A CN 109361854 A CN109361854 A CN 109361854A CN 201811241588 A CN201811241588 A CN 201811241588A CN 109361854 A CN109361854 A CN 109361854A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/60—Control of cameras or camera modules
- H04N23/67—Focus control based on electronic image sensor signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N17/00—Diagnosis, testing or measuring for television systems or their details
- H04N17/002—Diagnosis, testing or measuring for television systems or their details for television cameras
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/71—Circuitry for evaluating the brightness variation
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Abstract
The present invention relates to technical field of image processing, disclose a kind of video camera focus adjustment method, apparatus and system based on MTF, the method includes obtaining camera acquired image, described image is that light source arrival test card back reflection enters the image formed in camera；Five test zones are determined from described image, obtain the corresponding MTF curve of each test zone in five test zones；From the corresponding MTF curve of each test zone, the corresponding mtf value of specific frequency is chosen, and according to the mtf value of selection, determines the next step focus operations of the camera.
Description
Technical field
The present invention relates to technical field of image processing, more particularly to one kind to be based on MTF (Modulation Transfer
Function, i.e. modulation transfer function) video camera focus adjustment method, apparatus and system.
Background technique
It in the production process of video camera, needs to focus to video camera, i.e., using focus control to camera lens
The distance between the camera lens of mould group and photosensitive element are finely adjusted, and are directed at the focusing plane of camera lens with the sensing face of photosensitive element,
To reach optimal image quality.Currently, video camera focusing is all generally that manual operation is completed, alignment lens light is manually held
Focusing work is completed by artificial eye in source, and low efficiency, stability is poor, and the quality of product is unable to get guarantee, therefore, how
The efficiency and quality for promoting video camera focusing, are a technical issues that need to address.
Summary of the invention
The embodiment of the present invention provides kind of video camera focus adjustment method, an apparatus and system based on MTF, for promoting video camera tune
Burnt efficiency and quality.
In a first aspect, the embodiment of the present invention provides a kind of video camera focus adjustment method based on MTF, comprising:
Camera acquired image is obtained, described image enters in camera for light source arrival test card back reflection to be formed
Image；
Five test zones are determined from described image, and it is corresponding to obtain each test zone in five test zones
MTF curve；
From the corresponding MTF curve of each test zone, the corresponding mtf value of specific frequency is chosen, and according to selection
Mtf value, determine the next step focus operations of the camera.
Optionally, the test card is that the rectangular block of lateral repeated arrangement and the rectangular block of vertical repeated arrangement are alternately present
Test card, described image include according in the test card arrangement mode arrange rectangular block.
It is optionally, described that five test zones are determined from described image, comprising:
From described image, determine that the corresponding test zone of 0 visual field of picture centre and four 0.9 visual fields of angle are right respectively
Four test zones answered, determine five test zones altogether；
Wherein, any one test zone in five test sections includes at least one set of rectangular block, one group of rectangular block packet
Include the rectangular block of a transversely arranged rectangular block and a longitudinal arrangement.
Optionally, described to obtain the corresponding MTF curve of each test zone in five test zones, it specifically includes:
According to the intensity profile for at least one set of rectangular block for including in each test zone, calculated using sloping edge
Method, which calculates, obtains the corresponding one group of MTF curve of each test zone；
It is described to choose the corresponding mtf value of specific frequency from the corresponding MTF curve of each test zone, it is specific to wrap
It includes:
Specific frequency is chosen from one group of MTF curve for the corresponding one group of MTF curve of each test zone
The corresponding one group of mtf value of rate, and one group of mtf value is weighted and averaged, obtain each test zone corresponding one
A mtf value.
Optionally, mtf value described and according to selection, determines the next step focus operations of the camera, specifically includes:
If the corresponding mtf value of each test zone is greater than the corresponding MTF threshold value of the test zone, it is determined that institute
It states camera qualification and does not need to carry out next step focus operations.
Optionally, mtf value described and according to selection, determines the next step focus operations of the camera, specifically includes:
If the corresponding mtf value of each test zone is greater than the corresponding MTF threshold value of the test zone, according to figure
The mtf value of the selection of the corresponding test section of 0 visual field of inconocenter obtains focusing curve, and according to the variation tendency of focusing curve, draws
Lead next step focus operations.
Optionally, mtf value described and according to selection, determines the next step focus operations of the camera, specifically includes:
If there are the corresponding mtf values of at least one test zone to be less than at least one described survey in five test zones
Try the corresponding MTF threshold value in region, it is determined that the camera is unqualified, and continues focus operations, described after focusing
The corresponding mtf value in each region is corresponding greater than the test zone in five test zones in acquired image again for camera
MTF threshold value.
Second aspect, the embodiment of the present invention provide a kind of video camera focus control based on MTF, comprising:
Acquiring unit, for obtaining camera acquired image, described image be light source reach test card back reflection into
Enter the image formed in camera；
First determination unit for determining five test zones from described image, and obtains five test zones
In the corresponding MTF curve of each test zone；
Second determination unit, for it is corresponding to choose specific frequency from the corresponding MTF curve of each test zone
Mtf value, and according to the mtf value of selection, determine the next step focus operations of the camera.
Optionally, the test card is that the rectangular block of lateral repeated arrangement and the rectangular block of vertical repeated arrangement are alternately present
Test card, described image include according in the test card arrangement mode arrange rectangular block.
Optionally, first determination unit, is also used to:
From described image, determine that the corresponding test zone of 0 visual field of picture centre and four 0.9 visual fields of angle are right respectively
Four test zones answered, determine five test zones altogether；
Wherein, any one test zone in five test sections includes at least one set of rectangular block, one group of rectangular block packet
Include the rectangular block of a transversely arranged rectangular block and a longitudinal arrangement.
Optionally, first determination unit, is also used to:
According to the intensity profile for at least one set of rectangular block for including in each test zone, calculated using sloping edge
Method, which calculates, obtains the corresponding one group of MTF curve of each test zone；
Second determination unit, is also used to:
Specific frequency is chosen from one group of MTF curve for the corresponding one group of MTF curve of each test zone
The corresponding one group of mtf value of rate, and one group of mtf value is weighted and averaged, obtain each test zone corresponding one
A mtf value.
Optionally, second determination unit, is also used to:
If the corresponding mtf value of each test zone is greater than the corresponding MTF threshold value of the test zone, it is determined that institute
It states camera qualification and does not need to carry out next step focus operations.
Optionally, second determination unit, is also used to:
If the corresponding mtf value of each test zone is greater than the corresponding MTF threshold value of the test zone, according to figure
The mtf value of the selection of the corresponding test section of 0 visual field of inconocenter obtains focusing curve, and according to the variation tendency of focusing curve, draws
Lead next step focus operations.
Optionally, second determination unit, is also used to:
If there are the corresponding mtf values of at least one test zone to be less than at least one described survey in five test zones
Try the corresponding MTF threshold value in region, it is determined that the camera is unqualified, and continues focus operations, described after focusing
The corresponding mtf value in each region is corresponding greater than the test zone in five test zones in acquired image again for camera
MTF threshold value.
The third aspect, the embodiment of the present invention provide a kind of video camera focusing system based on MTF, including such as first aspect institute
State video camera and test card.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, embodiment will be described below
Needed in attached drawing be briefly described, it should be apparent that, the accompanying drawings in the following description is only of the invention some
Embodiment.
Fig. 1 is a kind of video camera focus adjustment method flow chart based on MTF provided in an embodiment of the present invention；
Fig. 2 is test card structural schematic diagram provided in an embodiment of the present invention；
Fig. 3 is that test zone schematic diagram is determined in image provided in an embodiment of the present invention；
Fig. 4 is MTF curve schematic diagram provided in an embodiment of the present invention；
Fig. 5 is that rectangular block positions schematic diagram in test zone provided in an embodiment of the present invention.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical solution of the present invention is clearly and completely described, it is clear that described embodiment is skill of the present invention
A part of the embodiment of art scheme, instead of all the embodiments.Based on the embodiment recorded in present specification, this field is general
Logical technical staff every other embodiment obtained without creative efforts, belongs to the technology of the present invention side
The range of case protection.
As shown in Figure 1, being a kind of video camera focus adjustment method based on MTF provided in an embodiment of the present invention, comprising:
Step 101: obtaining camera acquired image, described image is that light source arrival test card back reflection enters camera shooting
The image formed in head.
In the embodiment of the present invention, light source can be reflected into camera to be focused after reaching test card, wherein light source can
Think LED light source, is also possible to other kinds of light source, herein without any restrictions.
It in embodiments of the present invention, can after being reflected into camera to be focused after light source reaches test card
To obtain the collected image being reflected into camera of video camera, i.e. the test card graphic of acquisition camera candid photograph, in this hair
In bright embodiment, as shown in Fig. 2, test card is that the rectangular block of lateral repeated arrangement and the rectangular block of vertical repeated arrangement alternately go out
Existing test card, corresponding, the test card that the camera acquired image got in step 101 can be as shown in Figure 2
In image, i.e., the image that the rectangular block of lateral repeated arrangement and the rectangular block of vertical repeated arrangement are alternately present.
Step 102: five test zones are determined from the image of acquisition.
In embodiments of the present invention, it is contemplated that the image that video camera is clapped especially includes the video camera shooting figure of wide-angle lens
It is generated as might have distortion, therefore, after getting camera acquired image, before executing step 102, to step
101 images obtained carry out distortion correction, to reduce influence of the distortion to subsequent step.
After carrying out distortion correction to image, five test zones can be determined from the image of acquisition, wherein determine
Mode can be as shown in Figure 3: determine that the corresponding test zone of 0 visual field of picture centre and four angles 0.9 are regarded from image
Corresponding four test zones in field, determine five test zones altogether；
Wherein, any one test zone in five test sections include at least one set of rectangular block, one group of rectangular block includes
The rectangular block of one transversely arranged rectangular block and a longitudinal arrangement.
I.e. in embodiments of the present invention, the corresponding region of 0 visual field of picture centre can be selected as test first from image
Region selects corresponding four regions of four 0.9 visual fields of angle in image to select five from image altogether as test zone
A test zone, each of five test zones test zone includes at least one set of rectangular block, for example including one group of rectangle
Block includes the rectangular block of a transversely arranged rectangular block and a longitudinal arrangement, also may include two groups of rectangular blocks or three
Group rectangular block etc., herein for including one group of rectangular block.
Step 103: obtaining the corresponding MTF curve of each test zone in five test zones.
In embodiments of the present invention, after obtaining five test zones in image, five can also further be obtained
The corresponding MTF curve of each test zone in test zone, wherein can include at least according in each test zone
It is one group corresponding to calculate acquisition each test zone using sloping edge calculation method for the intensity profile of one group of rectangular block
MTF curve.
I.e. in embodiments of the present invention, five test zones, the i.e. corresponding test zone of 0 visual field of picture centre are being determined
And after corresponding four test zones of four 0.9 visual fields of angle, it can be tested according to each in five test zones
The image for one group of rectangular block for including in region calculates to obtain one group of rectangle in each test zone using the method for sloping edge
The corresponding one group of MTF curve of block.
For convenience of narration, five test zones are referred to as test zone 1, test zone 3, test zone 4, test section
Domain 5, then it is directed to test zone 1, it can be as shown in figure 4, being adopted according to the intensity profile of one group of rectangular block in test zone 1
The corresponding edge-spread function of rectangular block transversely arranged in 1 one groups of rectangular blocks of test zone is calculated with the method for sloping edge
Curve obtains line spread function then to edge-spread function derivation, finally does Fourier transformation to line spread function and obtains cross
To the corresponding MTF curve of rectangular block of arrangement, likewise, 1 one groups of squares of test zone can be calculated using the method for sloping edge
The corresponding MTF curve of the rectangular block of longitudinal arrangement in shape block is tested to obtain 1 corresponding one group of MTF curve of test zone
To the corresponding MTF curve of the rectangular block of arrangement and to the corresponding MTF curve of rectangular block of arrangement in region 1.
Similarly, can obtain respectively 2 corresponding one groups of MTF curves of test zone, 3 corresponding one groups of MTF curves of test zone,
5 corresponding one groups of MTF curves of 4 corresponding one groups of MTF curves of test zone and test zone.
Step 104: from the corresponding MTF curve of each test zone, choosing the corresponding mtf value of specific frequency.
In embodiments of the present invention, the specific frequency in step 104 can flexible setting according to actual needs, such as can be with
According to the frequency for the camera currently tested, the determining matched specific frequency of frequency with the camera can also choose MTF and appoint
The corresponding frequency of meaning numerical value or the corresponding MTF numerical value of optional frequency.Therefore, five each surveys of test zone in obtaining image
After trying the corresponding one group of MTF curve in region, it can be directed to the corresponding one group of MTF curve of each test zone, from one group of MTF
In curve, the corresponding one group of mtf value of specific frequency is chosen, and be weighted and averaged to one group of mtf value, obtain each test section
The corresponding mtf value in domain.
Here for MTF50 and continue with above-mentioned five test zones to be respectively test zone 1, test section with specific frequency
For domain 2, test zone 3, test zone 4 and test zone 5, then, for test zone 1, test can be obtained respectively
The corresponding one group of mtf value of MTF50 in one group of MTF curve, is then weighted and averaged this group of mtf value, one group of MTF in region 1
Each mtf value weight is 0.5 in value, and then obtains the MTF mean value of two mtf values, which is that test zone 1 is corresponding
A mtf value.Similarly, it is corresponding that test zone 2, test zone 3, test zone 4 and test zone 5 can be obtained
Mtf value, herein just not repeated description.
Step 105: judge the mtf value for whether being greater than the test zone in the corresponding mtf value of each test zone chosen,
If so, then follow the steps 106 or execute step 107, it is no to then follow the steps 108.
In embodiments of the present invention, it can be directed to the corresponding test section of five 0 visual fields of test zone, that is, picture centre in advance
Domain and corresponding four test zones of four 0.9 visual fields of angle, are set separately a MTF threshold value, for judging camera
Whether the clarity of corresponding test zone is qualified, i.e., a MTF threshold value is respectively arranged in five test zones, for sake of convenience,
The corresponding MTF threshold value of test zone 1 is known as MTF threshold value 1, the corresponding MTF threshold value of test zone 2 is known as MTF threshold value 2, test
The corresponding MTF threshold value in region 3 is known as that MTF threshold value 3, that the corresponding MTF threshold value of test zone 4 is known as MTF threshold value 4, test zone 5 is right
The MTF threshold value answered is known as MTF threshold value 5.
Then, the corresponding mtf value in each test section MTF threshold corresponding with its test zone that will be obtained according to step 104
Value is compared, it is assumed here that the corresponding mtf value of test zone 1 according to step 104 acquisition is mtf value 1, test zone 2 is right
The mtf value answered is mtf value 2, the corresponding mtf value of test zone 3 is mtf value 3, the corresponding mtf value of test zone 4 be mtf value 4,
And the corresponding mtf value of test zone 5 is mtf value 5, it is possible to by the corresponding mtf value 1 of test zone 1 and MTF threshold value 1 into
Row compares；The corresponding mtf value 2 and MTF threshold value 2 of test zone 2 is compared；The corresponding mtf value 3 of test zone 3 and MTF threshold value
3 are compared；The corresponding mtf value 4 and MTF threshold value 4 of test zone 4 is compared；The corresponding mtf value 5 of test zone 5 and MTF
Threshold value 5 is compared.
It in embodiments of the present invention, can if being greater than the mtf value of the test zone in the corresponding mtf value of each test zone
To execute step 106: determining that camera is qualified and do not need to carry out next step focus operations.
In embodiments of the present invention, if in step 105, the result that judges is the corresponding MTF of each test zone that chooses
When being greater than the mtf value of the test zone in value, then determine that the camera is qualified, at this moment can not need to carry out next step focusing
Operation.
I.e. when mtf value 1 is greater than MTF threshold value 1, mtf value 2 is greater than MTF threshold value 2, it is big that mtf value 3 is greater than MTF threshold value 3, mtf value 4
When MTF threshold value 4 and mtf value 5 are greater than MTF threshold value 5, then it is assumed that video camera clarity just calculates qualification, at this time can be without
It focuses in next step.
In embodiments of the present invention, if be greater than the mtf value of the test zone in the corresponding mtf value of each test zone,
Step 107 can also be performed: according to the mtf value of the selection of the corresponding test section of 0 visual field of picture centre, obtaining focusing curve, and
According to the variation tendency of focusing curve, next step focus operations are guided, to obtain more preferably clarity.
In the present embodiment, it is contemplated that when the corresponding mtf value of test zone each in five test zones is any greater than this
When the corresponding MTF threshold value of a test zone, although the clarity of video camera has had reached criterion of acceptability, but video camera is clear
Degree is not necessarily the clearest state that accommodated to, for example threshold value is set as 100, but the clarity maximum value in the region can
It if it is up to standard to be transferred to 101, but is not best state with up to standard 200, so when each test section in five test zones
When the corresponding mtf value in domain is greater than the test zone corresponding MTF threshold value, above-mentioned steps 101 can also be performed a plurality of times to step
104, the corresponding mtf value of specific frequency of the corresponding test zone of 0 visual field of picture centre of multiple images is obtained, then by multiple figures
The corresponding mtf value of the specific frequency of the corresponding test zone of 0 visual field of picture centre of picture forms focusing curve, then further according to tune
The variation tendency of burnt curve, real-time fitting calculate the optimal value of clarity, are finally guided in next step according to the optimal value of clarity
Focusing.
In embodiments of the present invention, if there are the corresponding mtf values of at least one test zone to be less than in five test zones
When the corresponding MTF threshold value of at least one test zone, step 108 can be executed: determine that camera is unqualified, and continue to adjust
Coke operation, each region is corresponding in five test zones in acquired image again for the camera after focusing
Mtf value is greater than the corresponding MTF threshold value of the test zone.
In embodiments of the present invention, when there is the corresponding MTF of one or more test zones in five test zones
Value is less than the corresponding MTF threshold value of the one or more test zone, then determines that the camera is unqualified, at this time, it is also necessary to after
Continuous focusing, and continue the collected figure again of the camera after judging to focus according to process shown in step 101 to step 105
The corresponding mtf value in each region is greater than the corresponding MTF threshold value of the test zone in five test zones as in.
For example, mtf value 3 is greater than MTF threshold value 3, mtf value when mtf value 1 is greater than MTF threshold value 1, mtf value 2 is less than MTF threshold value 2
4 are greater than MTF threshold value 4 and mtf value 5 when being greater than MTF threshold value 5, then it is assumed that video camera clarity is unqualified, can continue at this time
Focusing, and the acquired image again of the camera after focusing is obtained, five test zones are determined to acquired image again,
And the corresponding MTF curve of each test zone in five test zones is obtained, and from the corresponding MTF curve of each test zone
In, the corresponding mtf value of specific frequency is chosen, until being greater than the survey in the corresponding mtf value of each test zone for judging to choose
The mtf value in region is tried, herein just not repeated description.
So by the above method, available camera acquired image determines five from acquired image
Test zone, further obtains the corresponding MTF curve of each test zone in five test zones, and from each test zone pair
In the MTF curve answered, choose the corresponding mtf value of specific frequency, and according to the mtf value of selection, determine camera whether continue into
Row next step focus operations are greater than the mtf value of the test zone in the corresponding mtf value of that is, each test zone, can determine and take the photograph
Picture head qualification can also be focused without focusing according to the mtf value of the selection of the corresponding test section of 0 visual field of picture centre
Curve, and according to the variation tendency of focusing curve, next step focus operations are guided, to obtain more preferably clarity；It is surveyed when five
There are the corresponding mtf values of at least one test zone to be less than the corresponding MTF threshold value of at least one test zone in examination region, then really
It is unqualified to determine camera, and continues focus operations, five surveys in focusing rear camera again acquired image
It tries the corresponding mtf value in each region in region and is greater than the corresponding MTF threshold value of the test zone, so, not only realize video camera
The automation of focusing improves the efficiency and quality of video camera focusing.
Further, since the test card that in the embodiment of the present invention, uses is the rectangular block of lateral repeated arrangement and vertical
The test card that the rectangular block of repeated arrangement is alternately present, can take into account the video camera of more multifocal section of camera lens, and then avoid existing
In technology, for the camera lens of different burnt sections, the case where needing replacing different test cards, so, it may have the effect of save the cost
Fruit.
It can determine that 0 visual field of picture centre is corresponding in accordance with the following methods as a kind of optional mode, in step 102
Rectangular block in test zone and corresponding four test zones of four 0.9 visual fields of angle.Specifically, first to image into
For row median filtering to eliminate influence of the noise to edge detection, the effect of edge detection is to detect that the rectangular block in image is all
Edge, for determine key point prepare, wherein key point is the upper left corner, the lower left corner, the upper right corner and the lower right corner of finger-type block
Point can only determine three points in the upper left corner, the lower left corner, the upper right corner and bottom right angle point in practical applications, can by this three
The coordinate of a point can orient rectangular block.
Such as shown in Fig. 5, can be by line-scanning image, the condition that upper left angle point meets be angle point in edge image
(pixel value 255), the upper left corner (such as A) pixel intensity of upper left angle point is lower in gray level image, the lower right corner (such as B) as
Plain brightness is higher, and the upper right corner (such as G) pixel intensity is lower, upper left angle point can be determined by this method, then by a left side
Upper angle point, which scans downwards, is assured that out lower-left angle point, the condition of satisfaction be that (pixel value is angle point in edge image
255), in gray level image, upper left angle point (such as C) pixel intensity is lower, and angle point such as (D) pixel intensity in bottom right is higher,
Lower-left angle point is assured that out by this method, is scanned to the right by lower-left angle point and is assured that out bottom right angle point, satisfaction
Condition be angle point (pixel value 255) in edge image, in gray level image its upper left angle point (such as E) pixel intensity compared with
Low, bottom right angle point (such as F) pixel intensity is higher, has this method to be assured that out bottom right angle point；Searching for boundary is to remove
The extra edge of rectangular block shrinks edge schematic diagram as shown in Figure 5, has extra black surround edge on the left of image, the black surround edge pair
It calculates MTF curve to be affected, needs to be removed, by judging that the whether lower method of image left pixel brightness value can be with
Removed；Finally judge whether the number of rectangular block meets the requirements, expand search range if being unsatisfactory for requiring and continue to position,
Each region will at least orient the rectangular block of a transverse direction and a longitudinal direction, and the side for positioning lateral rectangular block is presented above
The method of method, longitudinal register rectangular block is similar with its.
Based on the same inventive concept, a kind of video camera focus control based on MTF, the dress are provided in the embodiment of the present invention
The specific implementation for the video camera focus adjustment method based on MTF set can be found in the description of above method embodiment part, repeat place
It repeats no more, which includes:
Acquiring unit, for obtaining camera acquired image, described image be light source reach test card back reflection into
Enter the image formed in camera；
First determination unit for determining five test zones from described image, and obtains five test zones
In the corresponding MTF curve of each test zone；
Second determination unit, for it is corresponding to choose specific frequency from the corresponding MTF curve of each test zone
Mtf value, and according to the mtf value of selection, determine the next step focus operations of the camera.
Optionally, the test card is that the rectangular block of lateral repeated arrangement and the rectangular block of vertical repeated arrangement are alternately present
Test card, described image include according in the test card arrangement mode arrange rectangular block.
Optionally, first determination unit, is also used to:
From described image, determine that the corresponding test zone of 0 visual field of picture centre and four 0.9 visual fields of angle are right respectively
Four test zones answered, determine five test zones altogether；
Wherein, any one test zone in five test sections includes at least one set of rectangular block, one group of rectangular block packet
Include the rectangular block of a transversely arranged rectangular block and a longitudinal arrangement.
Optionally, first determination unit, is also used to:
According to the intensity profile for at least one set of rectangular block for including in each test zone, calculated using sloping edge
Method, which calculates, obtains the corresponding one group of MTF curve of each test zone；
Second determination unit, is also used to:
Specific frequency is chosen from one group of MTF curve for the corresponding one group of MTF curve of each test zone
The corresponding one group of mtf value of rate, and one group of mtf value is weighted and averaged, obtain each test zone corresponding one
A mtf value.
Optionally, second determination unit, is also used to:
If the corresponding mtf value of each test zone is greater than the corresponding MTF threshold value of the test zone, it is determined that institute
It states camera qualification and does not need to carry out next step focus operations.
Optionally, second determination unit, is also used to:
If the corresponding mtf value of each test zone is greater than the corresponding MTF threshold value of the test zone, according to figure
The mtf value of the selection of the corresponding test section of 0 visual field of inconocenter obtains focusing curve, and according to the variation tendency of focusing curve, draws
Lead next step focus operations.
Optionally, second determination unit, is also used to:
If there are the corresponding mtf values of at least one test zone to be less than at least one described survey in five test zones
Try the corresponding MTF threshold value in region, it is determined that the camera is unqualified, and continues focus operations, described after focusing
The corresponding mtf value in each region is corresponding greater than the test zone in five test zones in acquired image again for camera
MTF threshold value.
Based on the same inventive concept, the embodiment of the present invention provides a kind of video camera focusing system based on MTF, including strictly according to the facts
Apply the video camera and test card in the video camera focus adjustment method based on MTF in example.
It should be understood by those skilled in the art that, the embodiment of the present invention can provide as method, system or computer program
Product.Therefore, complete hardware embodiment, complete software embodiment or reality combining software and hardware aspects can be used in the present invention
Apply the form of example.Moreover, it wherein includes the computer of computer usable program code that the present invention, which can be used in one or more,
The shape for the computer program product implemented in usable storage medium (including but not limited to magnetic disk storage and optical memory etc.)
Formula.
The present invention be referring to according to the method for the embodiment of the present invention, the process of equipment (system) and computer program product
Figure and/or block diagram describe.It should be understood that every one stream in flowchart and/or the block diagram can be realized by computer program instructions
The combination of process and/or box in journey and/or box and flowchart and/or the block diagram.It can provide these computer programs
Instruct the processor of general purpose computer, special purpose computer, Embedded Processor or other programmable data processing devices to produce
A raw machine, so that being generated by the instruction that computer or the processor of other programmable data processing devices execute for real
The device for the function of being specified in present one or more flows of the flowchart and/or one or more blocks of the block diagram.
These computer program instructions, which may also be stored in, is able to guide computer or other programmable data processing devices with spy
Determine in the computer-readable memory that mode works, so that it includes referring to that instruction stored in the computer readable memory, which generates,
Enable the manufacture of device, the command device realize in one box of one or more flows of the flowchart and/or block diagram or
The function of being specified in multiple boxes.
These computer program instructions also can be loaded onto a computer or other programmable data processing device, so that counting
Series of operation steps are executed on calculation machine or other programmable devices to generate computer implemented processing, thus in computer or
The instruction executed on other programmable devices is provided for realizing in one or more flows of the flowchart and/or block diagram one
The step of function of being specified in a box or multiple boxes.
Obviously, various changes and modifications can be made to the invention without departing from essence of the invention by those skilled in the art
Mind and range.In this way, if these modifications and changes of the present invention belongs to the range of the claims in the present invention and its equivalent technologies
Within, then the present invention is also intended to include these modifications and variations.
Claims (10)
1. a kind of video camera focus adjustment method based on MTF, which is characterized in that the described method includes:
Camera acquired image is obtained, described image is that light source arrival test card back reflection enters the figure formed in camera
Picture；
Five test zones are determined from described image, obtain the corresponding MTF of each test zone in five test zones
Curve；
From the corresponding MTF curve of each test zone, the corresponding mtf value of specific frequency is chosen, and according to the MTF of selection
Value, determines the next step focus operations of the camera.
2. the method as described in claim 1, which is characterized in that the test card is the rectangular block of lateral repeated arrangement and vertical
The test card that the rectangular block of repeated arrangement is alternately present, described image include the square arranged according to arrangement mode in the test card
Shape block.
3. method according to claim 2, which is characterized in that described to determine five test zones from described image, comprising:
Determine that the corresponding test zone of 0 visual field of picture centre and four 0.9 visual fields of angle are corresponding from described image
Four test zones determine five test zones altogether；
Wherein, any one test zone in five test sections includes at least one set of rectangular block, and one group of rectangular block includes one
The rectangular block of a transversely arranged rectangular block and a longitudinal arrangement.
4. method as claimed in claim 3, which is characterized in that described to obtain each test zone in five test zones
Corresponding MTF curve, specifically includes:
According to the intensity profile for at least one set of rectangular block for including in each test zone, using sloping edge calculation method
It calculates and obtains the corresponding one group of MTF curve of each test zone；
It is described from the corresponding MTF curve of each test zone, choose the corresponding mtf value of specific frequency, specifically include:
For the corresponding one group of MTF curve of each test zone, from one group of MTF curve, specific frequency pair is chosen
The one group of mtf value answered, and one group of mtf value is weighted and averaged, obtain the corresponding MTF of each test zone
Value.
5. method as claimed in claim 4, which is characterized in that mtf value described and according to selection determines the camera
Next step focus operations, specifically include:
If the corresponding mtf value of each test zone is greater than the corresponding MTF threshold value of the test zone, it is determined that described to take the photograph
As head is qualified and does not need to carry out next step focus operations.
6. method as claimed in claim 4, which is characterized in that mtf value described and according to selection determines the camera
Next step focus operations, specifically include:
If the corresponding mtf value of each test zone is greater than the corresponding MTF threshold value of the test zone, according in image
The mtf value of the selection of the corresponding test section of 0 visual field of the heart obtains focusing curve, and according to the variation tendency of focusing curve, under guidance
One step focus operations.
7. method as claimed in claim 4, which is characterized in that mtf value described and according to selection determines the camera
Next step focus operations, specifically include:
If there are the corresponding mtf values of at least one test zone to be less than at least one described test section in five test zones
The corresponding MTF threshold value in domain, it is determined that the camera is unqualified, and continues focus operations, the camera shooting after focusing
To be greater than the test zone corresponding for the corresponding mtf value in each region in five test zones in acquired image again for head
MTF threshold value.
8. a kind of video camera focus control based on MTF characterized by comprising
Acquiring unit, for obtaining camera acquired image, described image enters for light source arrival test card back reflection to be taken the photograph
As the image formed in head；
First determination unit for determining five test zones from described image, and obtains every in five test zones
The corresponding MTF curve of a test zone；
Second determination unit, for choosing the corresponding MTF of specific frequency from the corresponding MTF curve of each test zone
Value, and according to the mtf value of selection, determine the next step focus operations of the camera.
9. device as claimed in claim 8, which is characterized in that the test card is the rectangular block of lateral repeated arrangement and vertical
The test card that the rectangular block of repeated arrangement is alternately present, described image include the square arranged according to arrangement mode in the test card
Shape block；
First determination unit, is also used to:
From described image, determine that the corresponding test zone of 0 visual field of picture centre and four 0.9 visual fields of angle are corresponding
Four test zones determine five test zones altogether；
Wherein, any one test zone in five test sections includes at least one set of rectangular block, and one group of rectangular block includes one
The rectangular block of a transversely arranged rectangular block and a longitudinal arrangement.
10. a kind of video camera focusing system based on MTF, which is characterized in that including being taken the photograph as described in any one of claim 1-7
Camera and test card.
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Cited By (1)
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| CN111754568A (en) * | 2020-06-19 | 2020-10-09 | 上海保隆汽车科技股份有限公司 | Calibration pattern, calibration method and calibration plate device thereof |
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