CN110868584B - Focal length calibration method and device of image acquisition device - Google Patents
Focal length calibration method and device of image acquisition device Download PDFInfo
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- CN110868584B CN110868584B CN201810987956.3A CN201810987956A CN110868584B CN 110868584 B CN110868584 B CN 110868584B CN 201810987956 A CN201810987956 A CN 201810987956A CN 110868584 B CN110868584 B CN 110868584B
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Abstract
The embodiment of the invention provides a focal length calibration method and device of an image acquisition device. The focal length calibration method of the image acquisition device comprises the following steps: detecting the current clear value of the image on the imaging plate every other preset period; judging whether the back focus of the image acquisition device deviates or not according to the preset definition value and the current definition value; when the back focal of the image acquisition device is deviated, the position of the imaging plate is adjusted to calibrate the focal length, so that the burden of manual adjustment is reduced, the burden of maintenance personnel is reduced, the maintenance efficiency is improved, and the definition of an image is guaranteed.
Description
Technical Field
The invention relates to the technical field of image acquisition, in particular to a focal length calibration method and device of an image acquisition device.
Background
With the development of society, the use of image acquisition technology is more and more popular. Among them, pan-tilt cameras are widely used in large-scale projects such as safe cities, high-speed monitoring, forest fire prevention and the like, and are installed at high-rise points such as roofs and signal towers.
The existing camera is an assembly of a plurality of components, and when the temperature changes greatly or vibrates for a long time, the optical back focus of the existing camera is easy to deviate, and finally the existing camera is represented as the preset virtual focus originally set. Once problems occur, maintenance is difficult, long and inefficient due to the installation location and complexity of the components. Meanwhile, the monitoring function is also affected, and monitoring errors and omissions can be caused.
Disclosure of Invention
In order to solve the above problems, an object of the present invention is to provide a method and an apparatus for calibrating a focal length of an image capturing device.
In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:
in a first aspect, an embodiment of the present invention provides a method for calibrating a focal length of an image capture device, including:
detecting the current clear value of the image on the imaging plate every other preset period;
the current definition value is the definition value of an image formed by the imaging plate when the image acquisition device is located at a preset coordinate and a wide-angle position;
judging whether the back focus of the image acquisition device deviates or not according to a preset clear value and the current clear value; the preset definition value is the peak value of the definition value of the image formed by the imaging plate when the image acquisition device is positioned at a preset coordinate and a wide-angle position;
and when the back focus of the image acquisition device deviates, adjusting the position of the imaging plate to calibrate the focal length.
In a second aspect, an embodiment of the present invention further provides a focal length calibration apparatus for an image capture apparatus, including:
the detection unit is used for detecting the current clear value of the image on the imaging plate every other preset period;
the current definition value is the definition value of an image formed by the imaging plate when the image acquisition device is located at a preset coordinate and a wide-angle position;
the judging unit is used for judging whether the back focus of the image acquisition device deviates or not according to a preset clear value and the current clear value; the preset definition value is the peak value of the definition value of the image formed by the imaging plate when the image acquisition device is positioned at a preset coordinate and a wide-angle position;
and the adjusting unit is used for adjusting the position of the imaging plate to calibrate the focal length if the back focus of the image acquisition device deviates.
The method and the device for calibrating the focal length of the image acquisition device have the advantages that: detecting the current clear value of the image on the imaging plate every other preset period; judging whether the back focus of the image acquisition device deviates or not according to the preset clear value and the current clear value; when the back focal of the image acquisition device is deviated, the position of the imaging plate is adjusted to calibrate the focal length, so that the burden of manual adjustment is reduced, the burden of maintenance personnel is reduced, the maintenance efficiency is improved, and the definition of an image is guaranteed.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic application environment diagram illustrating a focus calibration method of an image capturing apparatus according to an embodiment of the present invention;
fig. 2 is a schematic flow chart illustrating a focus calibration method of an image capturing apparatus according to a first embodiment of the present invention;
fig. 3 is a flowchart illustrating a sub-step of step S102 of a focus calibration method for an image capturing apparatus according to a first embodiment of the present invention;
fig. 4 is a flowchart illustrating a sub-step of step S103 of the focus calibration method of the image capturing apparatus according to the first embodiment of the present invention;
fig. 5 is a schematic flowchart illustrating a focus calibration method for an image capturing apparatus according to a second embodiment of the present invention;
fig. 6 is a schematic flowchart illustrating a focal length calibration method for an image capturing apparatus according to a third embodiment of the present invention;
fig. 7 is a functional unit diagram of a focal length calibration apparatus of an image capturing apparatus according to an embodiment of the present invention.
Icon: 10-a first drive; 20-a second drive; 30-a third drive; 40-an image information processor; 50-a controller; 60-a memory; 70-peripheral interface; 200-a focal length calibration device of the image acquisition device; 201-a detection unit; 202-a judging unit; 203-adjusting unit.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The preferred embodiment of the present invention provides a method for calibrating a focal length of an image capturing device, which is applied to a controller 50. The image acquisition device can adopt but not limited to a video camera or a still camera, and comprises: an imaging plate and a focusing lens group. As shown in fig. 1, the controller 50 is electrically connected to the first driving device 10, the second driving device 20, the third driving device 30, the image information processor 40, the memory 60, and the peripheral interface 70, respectively.
The first driving device 10 is used for receiving the instruction of the controller 50 and driving the imaging plate to move. The first driving device 10 may employ a stepping motor.
The second driving device 20 is used for receiving the instruction of the controller 50 and driving the focusing lens group to zoom. The second driving device 20 may employ a dc motor.
The third driving device 30 is used for receiving the instruction of the controller 50 and driving the focusing lens group to focus. The third driving device 30 may employ a dc motor.
The image information processor 40 is used to capture an image on the imaging plate and convert it into a value of sharpness of the image, i.e., a sharpness value, and transmit the sharpness value to the controller 50.
The memory 60 can be used to store software programs and modules, such as program instructions/modules corresponding to the image processing apparatus and method in the embodiment of the present invention, and the focal length calibration apparatus 200 of the image capturing apparatus. The controller 50 executes various functional applications and data processing, such as a focus calibration method of the image capturing apparatus provided by the embodiment of the present invention, by executing software programs and modules stored in the memory 60. The memory 60 may also be used to store other data transmitted by the controller 50.
The focus calibration apparatus 200 of the image capturing apparatus includes at least one software function module that can be stored in the memory 60 in the form of software or firmware (firmware) or is fixed in an Operating System (OS) of the controller 50.
The peripheral interface 70 is used for connecting an external input device, and a user can adjust and modify the focus calibration apparatus 200 of the image capturing device through the external input device.
The method for calibrating the focal length of the image capturing device according to the first embodiment of the present invention is applied to the controller 50, and the specific steps are as shown in fig. 2:
step S101: and detecting the current clear value, the front clear value and the rear clear value of the image on the imaging plate every other preset period.
The front clear value is the clear value of an image formed after the imaging plate moves a preset distance from the current position along the direction close to the focusing lens group; the rear clear value is the clear value of an image formed after the imaging plate moves a preset distance from the current position along the direction far away from the focusing lens group; the current definition value is the definition value of an image formed by the imaging plate when the image acquisition device is positioned at a preset coordinate and a wide-angle position; the current position is the position of the imaging plate when the image on the imaging plate corresponds to the current definition value.
The preset period may be preset to 12 hours, 48 hours, 78 hours, etc., and is not limited herein.
The controller 50 controls the second driving device 20 to drive the focusing lens group to zoom to the wide-angle position every time of a preset period. At this time, the image information processor 40 collects the image on the imaging plate and converts the image into a sharpness value of the image, which is the current sharpness value. The image information processor 40 transmits the current sharpness value to the controller 50.
After receiving the current sharpness value transmitted from the image information processor 40, the controller 50 controls the first driving device 10 to drive the imaging plate to move a preset distance from the current position in a direction approaching the focusing lens group. At this time, the image information processor 40 collects the image on the imaging plate and converts the image into a sharpness value of the image, which is the front sharpness value. The image information processor 40 transmits the front clear value to the controller 50.
Similarly, a back sharpness value of the image on the imaging plate is detected.
The preset distance can be adaptively modified according to different image acquisition devices.
Step S102, according to a preset definition value, the current definition value, the front definition value and the rear definition value, judging whether a rear focus of the image acquisition device is shifted? If yes, go to step S103; if not, go to step S101.
The preset definition value is the peak value of the definition value of the image formed by the imaging plate when the image acquisition device is positioned at a preset coordinate and a wide-angle position. The preset coordinates are preset by a worker when the image acquisition device is installed and are used for controlling the angle, the direction and the like of the image acquisition device, and understandably, the image acquisition device is located under different preset coordinates, and the acquired images are different.
Specifically, the substeps of step S102 shown in fig. 3 include:
step S1021: is it determined whether the product of the preset sharpness value and a preset first threshold value is greater than the current sharpness value? If yes, go to step S1022; if not, go to step S101.
Specifically, the preset first threshold value ranges from 80% to 85%. And when the product of the preset definition value and the preset first threshold value is greater than the current definition value, it indicates that the definition value of the image at the moment exceeds the allowable error range, and step S1022 is executed in order to further determine whether the back focus of the image acquisition device is shifted.
Step S1022: determine whether a product of the current sharpness value and a preset second threshold is greater than a maximum of the front sharpness value and the rear sharpness value? If yes, executing step S101; if not, step S103 is executed.
Specifically, the preset second threshold value ranges from 80% to 85%.
And if the product of the current clear value and a preset second threshold value is less than or equal to the maximum value of the front clear value and the rear clear value, indicating that the current clear value is not in an allowable error range, thereby indicating that the back focus of the image acquisition device is shifted. Through the two judgments in the steps S1021 and S1022, the problem of misjudgments caused by environmental influence factors such as rain and fog can be solved through double verification, and the accuracy of the detection result is improved.
Step S103: adjusting the imaging plate position to calibrate the focal length.
Specifically, the sub-steps of step S103 shown in fig. 4 include:
step S1031: and controlling the first driving device 10 to drive the imaging plate to move to the first position at the wide-angle position so that the image on the imaging plate is in the first clearest state.
Specifically, the controller 50 controls the first driving device 10 to drive the imaging plate to move stepwise.
The controller 50 receives and records the definition value of the image on the imaging plate transmitted by the image information processor 40 every time the controller moves one step, and records the position of the imaging plate corresponding to the definition value.
And calculating the peak value of the clear value according to a hill climbing algorithm, and inquiring a first position associated with the peak value according to the peak value of the clear value. Because the arrangement of the clear values of the image on the imaging plate appears as a mountain when the imaging plate is moved from the position allowed to be farthest away from the focusing lens group to the position closest to the focusing lens group.
And controlling a first driving device 10 to drive the imaging plate to move to the first position. Thereby ensuring that the image on the imaging plate is in a first position in a first sharpest state.
Step S1032: and controlling a second driving device 20 to drive the focusing lens group to zoom to the longest focus position.
Specifically, the controller 50 controls the second driving device 20 to drive the focusing lens group to zoom to the longest focal position while keeping the imaging plate at the first position.
Step S1033: controlling a third driving device 30 to drive the group of focusing lenses at the longest focus position to focus to a second position at which the image on the imaging plate is in a second sharpest state.
Specifically, the controller 50 controls the third driving device 30 to drive the focusing lens group to move.
The controller 50 receives and records the sharpness value of the image on the imaging plate transmitted by the image information processor 40, and records the position of the focusing lens group corresponding to the sharpness value.
And calculating the peak value of the clear value according to a hill climbing algorithm, and inquiring a second position associated with the peak value according to the peak value of the clear value. Because the arrangement of the clear values of the image on the imaging plate also appears as a mountain when the group of focusing lenses is moved. When the focusing lens group is located at a second position associated with the peak, the sharpness of the image on the imaging plate is highest.
The controller 50 controls the third driving device 30 to drive the focusing lens group to focus to the second position.
Therefore, the first position is the position where the imaging plate is located when the image on the imaging plate is clearest in the state that the focusing lens group is focused to the second position and zoomed to the longest focal position.
Step 1034: keeping the focusing lens group focused on the second position, and controlling the second driving device 20 to drive the focusing lens group to zoom again to the wide-angle position.
Step 1035: and controlling the first driving device 10 to drive the imaging plate to move to the third position in the wide-angle position so that the image on the imaging plate is in the third clearest state.
In the same manner as in step S1031, the third position is the position of the imaging plate when the image on the imaging plate is clearest in the state where the focusing lens group is focused to the second position and zoomed to the wide-angle position.
Step 1036: determine whether a distance value between the third position and the first position is less than a preset third threshold? If yes, go to step S1037; if not, step S1038 is performed.
Specifically, when the distance value between the third position and the first position is smaller than a preset third threshold, it indicates that when the focusing lens group is located at the wide angle position or the longest focus position, the position distance of the imaging plate corresponding to the sharpest state of the image on the imaging plate is very close, and within an allowable error range, it indicates that when the imaging plate is located at the third position, the focusing lens group zooms to the wide angle position or zooms to the longest focus position to obtain an image with ideal sharpness.
If the distance value between the third position and the first position is greater than or equal to a preset third threshold, it indicates that when the imaging plate is located at the third position, the image condition that the ideal definition can be obtained by zooming the focusing lens group to the wide angle position or zooming to the longest focal position is not satisfied.
Step S1037: and calibrating the focal length according to the third position.
Step S1038: and covering the first position with the third position, generating a new first position, and deleting the existing second position and the third position.
Specifically, for example, the recorded first position is S, the second position is M, and the third position is N. The third position covers the first position, i.e. the new first position is N. Deleting the second location and the third location.
The method for calibrating the focal length of the image capturing device according to the second embodiment of the present invention is applied to the controller 50, and the specific steps are as shown in fig. 5:
step S201: and detecting the current clear value of the image on the imaging plate every other preset period.
Step S202: is it determined whether the product of the preset sharpness value and a preset first threshold value is greater than the current sharpness value? If yes, go to step S203; if not, step S201 is executed.
Step S203: and detecting a front clear value and a rear clear value of the image on the imaging plate.
Step S204: determine whether a product of the current sharpness value and a preset second threshold is greater than a maximum of the front sharpness value and the rear sharpness value? If yes, go to step S201; if not, go to step S205.
Step S205: adjusting the imaging plate position to calibrate the focal length.
Gradually detecting and judging, and when the checking result in the step S202 is negative, the rest steps are not needed to be executed, the operation burden of the image acquisition device is reduced, and the operation efficiency of the equipment is improved
The method for calibrating the focal length of the image capturing device according to the third embodiment of the present invention is applied to the controller 50, and the specific steps are as shown in fig. 6:
step S301: and detecting the current clear value of the image on the imaging plate every preset period.
Step S302: is the back focus of the image capture device offset determined from a preset sharpness value and the current sharpness value? If yes, go to step S303; if not, step S301 is executed.
Specifically, whether the product of the preset clear value and a preset first threshold value is smaller than or equal to the current clear value is judged, and if yes, the back focus of the image acquisition device is not shifted; and if not, the back focus of the image acquisition device is deviated.
Step S303: adjusting the imaging plate position to calibrate the focal length.
Referring to fig. 7, fig. 5 is a focal length calibrating apparatus 200 of an image capturing device according to a preferred embodiment of the invention. It should be noted that the basic principle and the generated technical effect of the focal length calibrating device 200 of the image capturing apparatus provided in the present embodiment are the same as those of the above embodiments, and for the sake of brief description, no part of the present embodiment is mentioned, and reference may be made to the corresponding contents in the above embodiments.
The focus calibration apparatus 200 of the image pickup apparatus is applied to the controller 50, and the focus calibration apparatus 200 of the image pickup apparatus includes:
the detecting unit 201 is used for detecting the current definition value of the image on the imaging plate every preset period. Specifically, the detection unit 201 may perform step S301.
The current definition value is the definition value of an image formed by the imaging plate when the image acquisition device is located at a preset coordinate and a wide-angle position.
The detecting unit 201 is further configured to detect a front sharpness value and a rear sharpness value of the image on the imaging plate every the preset period. Therefore, the detection unit 201 may perform steps S101, S201, and S203.
The front clear value is the clear value of an image formed after the imaging plate moves a preset distance from the current position along the direction close to the focusing lens group; the rear clear value is the clear value of an image formed after the imaging plate moves a preset distance from the current position along the direction far away from the focusing lens group; the current position is a position of the imaging plate corresponding to the current sharpness value.
The determining unit 202 is configured to determine whether a back focus of the image capturing device is shifted according to a preset sharpness value and the current sharpness value, or according to the preset sharpness value, the current sharpness value, the front sharpness value, and the back sharpness value. Specifically, the determination unit 202 may perform steps S102, S302.
The preset definition value is the peak value of the definition value of the image formed by the imaging plate when the image acquisition device is positioned at a preset coordinate and a wide-angle position.
The determining unit 202 is specifically configured to determine whether a product of the preset sharpness value and a preset first threshold is smaller than or equal to the current sharpness value, and if not, the back focus of the image capturing apparatus is shifted.
The determining unit 202 may further be specifically configured to determine whether a product of the preset clear value and a preset first threshold is greater than the current clear value. Specifically, the determination unit 202 may perform steps S1021 and S202.
When the product of the preset distinct value and the first threshold is greater than the current distinct value, the determining unit 202 may be further specifically configured to determine whether the product of the current distinct value and a preset second threshold is greater than a maximum value of the front distinct value and the rear distinct value. Specifically, the determination unit 202 may perform steps S1022 and S204.
And if the product of the preset clear value and the first threshold is larger than the current clear value, and the product of the current clear value and the second threshold is smaller than or equal to the maximum value of the front clear value and the rear clear value, the rear focus of the image acquisition device is deviated.
An adjusting unit 203, configured to adjust the position of the imaging plate to calibrate the focal length if the back focus of the image capturing device deviates. Specifically, the adjusting unit 203 may perform step S103, step S203, and step S303.
Specifically, the adjusting unit 203 includes:
and the first control module is used for controlling the first driving device 10 to drive the imaging plate to move to the first position at the wide angle position so that the image on the imaging plate is in the first clearest state. Specifically, the first control module may perform step S1031.
And a second control module, configured to control the second driving device 20 to drive the focusing lens group to zoom to the longest focus position. Specifically, the second control module may perform step S1032.
And a third control module, configured to control a third driving device 30 to drive the focusing lens group in the longest focus position to focus to a second position where the image on the imaging plate is in the second clearest state. Specifically, the third control module may perform step S1033.
The second control module is further configured to keep the focusing lens group focused at the second position, and control the second driving device 20 to drive the focusing lens group to zoom to the wide-angle position. Specifically, the second control module may perform step S1034.
The first control module is further configured to control the first driving device 10 to drive the imaging plate to move to a third position in the wide-angle position, so that the image on the imaging plate is in a third clearest state. Specifically, the first control module may perform step S1035.
The determining unit 202 is further configured to determine whether a distance value between the third position and the first position is smaller than a preset third threshold. Specifically, the determination unit 202 may perform step S1036.
And the execution module is used for calibrating the focal length according to the third position if the distance value between the third position and the first position is smaller than a preset third threshold value. Specifically, the execution module may execute step S1037.
And the resetting module is used for covering the third position on the first position to generate a new first position and deleting the existing second position and the third position if the distance value between the third position and the first position is greater than or equal to a preset third threshold value. Specifically, the reset module can perform step S1038.
To sum up, the focus calibration method and apparatus of the image capturing device according to the preferred embodiment of the present invention include: firstly, detecting the current definition value of an image on an imaging plate every other preset period, or detecting the current definition value, the front definition value and the rear definition value of the image on the imaging plate; judging whether the back focus of the image acquisition device deviates or not according to the preset definition value and the current definition value or according to the preset definition value, the current definition value, the front definition value and the back definition value; when the back focus of the image acquisition device deviates, the position of the imaging plate is adjusted to calibrate the focal length, and the controller automatically detects, judges and adjusts the back focus, so that the burden of manual adjustment is reduced, the burden of maintenance personnel is reduced, the maintenance efficiency is improved, and the definition of an image is guaranteed; secondly, judging whether the rear focus of the image acquisition device deviates according to whether the product of the preset definition value and a preset first threshold value is larger than the current definition value or not and whether the product of the current definition value and a preset second threshold value is larger than the maximum value of the front definition value and the rear definition value or not, and performing double verification to solve the problem of misjudgment caused by environmental influence factors such as rain and fog and improve the accuracy of a detection result; then, if the distance value between the third position and the first position is smaller than a preset third threshold, calibrating the focal length according to the third position, thereby ensuring the definition of an image on an imaging plate in the process that a focusing lens group is zoomed from a wide angle position to a longest focal position when the imaging plate is at the third position; and finally, gradually detecting and judging, and when the check result in the step S202 is negative, the rest steps are not required to be executed, so that the operation burden of the image acquisition device is reduced, and the operation efficiency of the equipment is improved.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other ways. The apparatus embodiments described above are merely illustrative, and for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, the functional modules in the embodiments of the present invention may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.
The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A focal length calibration method of an image acquisition device is characterized by comprising the following steps:
detecting the current clear value of the image on the imaging plate every other preset period;
the current definition value is the definition value of an image formed by the imaging plate when the image acquisition device is located at a preset coordinate and a wide-angle position;
judging whether the back focus of the image acquisition device deviates or not according to a preset clear value and the current clear value; the preset definition value is the peak value of the definition value of the image formed by the imaging plate when the image acquisition device is positioned at a preset coordinate and a wide-angle position;
when the back focus of the image acquisition device deviates, adjusting the position of the imaging plate to calibrate the focal length;
the method for calibrating the focal length of the image acquisition device further comprises the following steps:
detecting a front clear value and a rear clear value of an image on the imaging plate every other preset period;
the front clear value is the clear value of an image formed after the imaging plate moves a preset distance from the current position along the direction close to the focusing lens group; the rear clear value is the clear value of an image formed after the imaging plate moves a preset distance from the current position along the direction far away from the focusing lens group; the current position is the position of the imaging plate when the image on the imaging plate corresponds to the current definition value;
the step of judging whether the back focus of the image acquisition device deviates or not according to a preset clear value and the current clear value comprises the following steps:
judging whether the product of the preset clear value and a preset first threshold value is larger than the current clear value or not;
if the product of the preset definition value and a preset first threshold value is larger than the current definition value, judging whether the product of the current definition value and a preset second threshold value is larger than the maximum value of the front definition value and the rear definition value;
and if the product of the current clear value and a preset second threshold value is less than or equal to the maximum value of the front clear value and the rear clear value, the rear focus of the image acquisition device is deviated.
2. The focus calibration method of an image capture device according to claim 1, wherein said step of adjusting said imaging plate position to calibrate the focus comprises:
controlling a first driving device to drive the imaging plate to move to a first position at a wide-angle position so that an image on the imaging plate is in a first clearest state;
controlling a second driving device to drive the focusing lens group to zoom to the longest focus position, and controlling a third driving device to drive the focusing lens group at the longest focus position to focus to a second position at which an image on the imaging plate is in a second clearest state;
keeping the focusing lens group focused at the second position, and controlling the second driving device to drive the focusing lens group to zoom again to a wide-angle position; controlling the first driving device to drive the imaging plate to move to a third position at the wide-angle position so that the image on the imaging plate is in a third clearest state;
and if the distance value between the third position and the first position is smaller than a preset third threshold, calibrating the focal length according to the third position.
3. The focal length calibration method of an image capturing device as claimed in claim 2, wherein the step of controlling the first driving device to drive the imaging plate to move to the first position at the wide angle position so that the image on the imaging plate is in the first sharpest state comprises:
controlling the first driving device to drive the imaging plate to move step by step;
recording the clear value of the image on the imaging plate and the position of the imaging plate corresponding to the clear value in each moving step;
calculating a peak value of the clear value according to a hill climbing algorithm, and inquiring a first position associated with the peak value according to the peak value of the clear value;
and controlling the first driving device to drive the imaging plate to move to the first position.
4. The method for calibrating the focal length of an image capturing device according to claim 2, wherein the step of controlling the third driving device to drive the group of focusing lenses at the longest focal position to focus at the second position, which makes the image on the imaging plate at the second sharpest state, comprises:
controlling the third driving device to drive the focusing lens group to move;
recording a clear value of an image on the imaging plate and a position of the focusing lens group corresponding to the clear value;
calculating a peak value of the clear value according to a hill climbing algorithm, and inquiring a second position associated with the peak value according to the peak value of the clear value;
and controlling the third driving device to drive the focusing lens group to move to the second position.
5. A focus calibration apparatus for an image pickup apparatus, comprising:
the detection unit is used for detecting the current clear value of the image on the imaging plate every other preset period;
the current definition value is the definition value of an image formed by the imaging plate when the image acquisition device is located at a preset coordinate and a wide-angle position;
the judging unit is used for judging whether the back focus of the image acquisition device deviates or not according to a preset clear value and the current clear value; the preset definition value is the peak value of the definition value of the image formed by the imaging plate when the image acquisition device is positioned at a preset coordinate and a wide-angle position;
the adjusting unit is used for adjusting the position of the imaging plate to calibrate the focal length if the back focus of the image acquisition device deviates;
the detection unit is also used for detecting the front clear value and the rear clear value of the image on the imaging plate every other preset period;
the front clear value is the clear value of an image formed after the imaging plate moves a preset distance from the current position along the direction close to the focusing lens group; the rear clear value is the clear value of an image formed after the imaging plate moves a preset distance from the current position along the direction far away from the focusing lens group; the current position is the position of the imaging plate when the image on the imaging plate corresponds to the current definition value;
the judging unit is specifically configured to judge whether a product of the preset clear value and a preset first threshold is greater than the current clear value;
if the product of the preset clear value and a preset first threshold is greater than the current clear value, the judging unit is further configured to judge whether the product of the current clear value and a preset second threshold is greater than the maximum value of the front clear value and the rear clear value;
and if the product of the current clear value and a preset second threshold value is less than or equal to the maximum value of the front clear value and the rear clear value, the rear focus of the image acquisition device is deviated.
6. The focal length calibration apparatus of an image capturing device according to claim 5, wherein the adjusting unit comprises:
the first control module is used for controlling the first driving device to drive the imaging plate to move to the first position under the wide-angle position so that the image on the imaging plate is in the first clearest state;
the second control module is used for controlling the second driving device to drive the focusing lens group to zoom to the longest focus position;
the third control module is used for controlling a third driving device to drive the focusing lens group in the longest focus position to focus to a second position which enables the image on the imaging plate to be in a second clearest state;
the second control module is further configured to keep the focusing lens group focused at the second position, and control the second driving device to drive the focusing lens group to zoom to a wide-angle position;
the first control module is further used for controlling the first driving device to drive the imaging plate to move to a third position in the wide-angle position, so that the image on the imaging plate is in a third clearest state;
the judging unit is further configured to judge whether a distance value between the third position and the first position is smaller than a preset third threshold;
and the execution module is used for calibrating the focal length according to the third position if the distance value between the third position and the first position is smaller than a preset third threshold value.
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