Imaging disturbance detecting device

Abstract

An imaging disturbance detection device (100) detects disturbance of imaging in a camera unit (20) and comprises a detection unit (314). The detection unit (314) outputs a first detection signal when the sharpness of the captured image that has been captured by the camera unit (20) changes by a prescribed amount or more from a predetermined reference sharpness at preset positions (72-74). The first detection signal indicates detection of a decrease in the sharpness of the captured image from the camera unit (20) at the preset positions (72-74).

Description

Filming tampering detection device

[0001] The present invention relates to a photography tampering detection device.

[0002] Patent Document 1 proposes a technique for calculating the brightness difference between an image from a surveillance camera and a reference image for each pixel, and determining whether or not camera interference has occurred based on the number of changed pixels where the brightness difference is greater than a first threshold value.

[0003] Japanese Patent Application Laid-Open No. 2008-77517

[0004] An object of the present invention is to provide a photography tampering detection device and a photography tampering detection method that can accurately detect tampering with photography by a surveillance camera.

[0005] The photography tampering detection device according to the first aspect of this embodiment is a device that detects photography tampering of a camera, and includes a detection unit that outputs a first detection signal indicating the detection of a change in sharpness of the image captured by the camera at the preset position when it detects that the sharpness of the image captured by the camera has changed by a predetermined amount or more from a predetermined reference sharpness of the preset position.

[0006] A photography interference detection device according to a second aspect of this embodiment is a device for detecting photography interference of a camera, and includes a detection unit that outputs a detection signal indicating detection of photography interference of the preset position when the focus of the camera after autofocus operation deviates from the reference focus position of the preset position.

[0007] A method for detecting interference with photography according to a third aspect of this embodiment is a method for detecting interference with photography of a camera, which, when it detects that the sharpness of an image captured by the camera has changed by a predetermined amount or more from a predetermined reference sharpness of a preset position, outputs a first detection signal indicating the detection of a change in sharpness of the image captured by the camera at the preset position.

[0008] A fourth aspect of the present embodiment of a method for detecting interference with photography of a camera is a method for detecting interference with photography of a camera, and when the focus of the camera after autofocus operation deviates from the reference focus position of a preset position, a detection signal indicating detection of interference with photography of the preset position is output.

[0009] According to this embodiment, it is possible to provide a photography tampering detection device and a photography tampering detection method that can accurately detect tampering with photography by a surveillance camera.

[0010] FIG. 1 is a diagram showing an outline of the configuration of a surveillance camera device equipped with a photography interference detection device according to a first embodiment. FIG. 2 is a diagram showing an example of preset positions set by the camera unit of FIG. 1. FIG. 3 is a diagram showing photography information registered for the preset positions of FIG. 2. FIG. 4 is a flowchart showing an example of a processing procedure executed by the photography interference detection device of FIG. 1. FIG. 5 is a diagram showing an example of a relationship between expected patterns of photography interference in the surveillance camera device of FIG. 1 and events occurring in each pattern. FIG. 6 is a diagram showing an example of a state in which one of the preset positions of FIG. 2 is blocked from the field of view of the lens block by an obstruction. FIG. 7 is a flowchart showing an example of a processing procedure executed by the photography interference detection device according to a second embodiment. FIG. 8 is a flowchart showing an example of a processing procedure executed by the photography interference detection device according to a third embodiment. FIG. 9 is a flowchart showing an example of a processing procedure executed by the photography interference detection device according to a fourth embodiment.

[0011] Hereinafter, first to fourth embodiments will be described with reference to the drawings. The same or equivalent parts or components are designated by the same reference numerals throughout the drawings.

[0012] The following embodiments are examples of devices and the like that embody the technical concept of the present invention. The technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of each component to those described below.

[0013] [First Embodiment] This embodiment is an embodiment that detects photography tampering using changes in sharpness. As shown in Fig. 1, a photography tampering detection device 100 of the first embodiment is provided in a surveillance camera device 10 that outputs captured images of a monitored space (not shown). The surveillance camera device 10 has a camera unit 20 and a controller 30. The photography tampering detection device 100 can be configured using, for example, the controller 30.

[0014] The camera unit 20 is installed, for example, at a high location in the monitored space. The high location may be, for example, the ceiling of the monitored space. The camera unit 20 may be, for example, a PTZ (Pan-Tilt-Zoom) camera equipped with a tilt mechanism and a pan mechanism (neither of which are shown) that change the shooting direction up, down, left, or right. The camera unit 20 includes a lens block 21, a zoom adjustment unit 22, a focus adjustment unit 23, and an imaging unit 24.

[0015] The lens block 21 has a lens group consisting of a plurality of lenses. Each lens constituting the lens group can move in the direction of its respective optical axis. The zoom adjustment unit 22 and the focus adjustment unit 23 individually move each lens in the lens group in the direction of the lens optical axis to optically adjust the zoom position of the lens block 21 and the focal position of the lens block 21, which correspond to the magnification of the image of the subject, respectively.

[0016] The imaging unit 24 is an image sensor having a solid-state imaging element. The solid-state imaging element may be, for example, a complementary metal-oxide-semiconductor (CMOS) or a charge-coupled device (CCD). An image is formed on the imaging unit 24 by light that has passed through the lens block 21. The imaging unit 24 photoelectrically converts the light of the image formed on the imaging unit 24 and outputs an image signal that is an electrical signal of the image formed on the imaging unit 24.

[0017] The camera unit 20 can perform patrol photography by sequentially switching the photography position among multiple preset positions. In addition to patrol photography, the camera unit 20 can also photograph any position desired by the user by operating a control panel (not shown). After photographing any position with the camera unit 20 through user operation, the original photography position can be registered as a preset position, allowing the camera unit 20 to return to the original photography position. The preset positions of the camera unit 20 can be registered in advance. FIG. 2 shows a case where preset positions 72 to 74 are used as conditions for photographing three gates 62 to 64 installed on a wall 61 of a logistics warehouse 60, which is a monitored space. In this example, the camera unit 20 is installed on the ceiling 65 of the logistics warehouse 60.

[0018] 3 shows the shooting information by the camera unit 20 that is registered in advance for each of the preset positions 72 to 74. In other words, a preset position is a shooting condition, and a combination of parameters such as "Pan," "Tilt," "Zoom," "Focus," "Focus Range," "Sharpness," and "Sharpness Range" is registered as an example of shooting information, and multiple preset positions can be stored in the storage device 320. For example, if the camera unit 20 is a PTZ camera, the parameters "Pan," "Tilt," and "Zoom" are registered in the storage device 320 as the shooting information for the preset positions 72 to 74.

[0019] "Pan" is the horizontal swing angle of the camera unit 20 from a reference direction (not shown), and "Tilt" is the vertical swing angle of the camera unit 20 from the reference direction, both in degrees. "Zoom" is the optical zoom magnification of the subject by the zoom lens 211.

[0020] For each preset position 72-74, where the "Pan," "Tilt," and "Zoom" parameters are registered as shooting information, a "Focus" parameter is initially set. "Focus" is the distance from the principal point of the lens block 21 to the focal point, measured in millimeters (mm). The principal point of the lens block 21 is the center point of a single optically equivalent lens if the lens block 21 were replaced with that lens. When the "Focus" parameter is initially set, the camera unit 20 captures each of the preset positions 72-74 using the registered "Pan," "Tilt," and "Zoom" parameters and performs autofocusing. When capturing images of each of the preset positions 72-74 in the state shown in FIG. 2 to set the "Focus" parameter, the lens block 21 focuses on each of the gates 62-64 through the autofocusing operation performed by the camera unit 20. The focus of the lens block 21 at this time is the initial setting value in the shooting information for each preset position 72 to 74, i.e., the reference focus position, and is registered in the storage device 320 as "Focus" along with the parameters "Pan," "Tilt," and "Zoom." The registered reference focus positions ("Focus") for each preset position 72 to 74 can be used, for example, to detect interference with shooting by the surveillance camera device 10. Interference with shooting by the surveillance camera device 10 can be detected, for example, based on whether the focus of the lens block 21 during shooting at each preset position 72 to 74 has changed from the reference focus position. Whether the focus of the lens block 21 has changed from the reference focus position can be determined by comparing the focus of the lens block 21 after autofocus operation with "Focus," i.e., the reference focus position, during shooting at each preset position 72 to 74. The focus position is also referred to as the focus position.

[0021] In the example shown in FIG. 3 , a "Focus Range" is added to the imaging information for preset positions 72 to 74. Even if the subject being imaged by the camera unit 20 remains unchanged, the focus of the lens block 21 may shift slightly due to changes in imaging conditions, such as vibration of the camera unit 20 or changes in lighting. The "Focus Range" indicates the permissible range of focus deviation of the lens block 21 from the reference focus position when determining whether the focus of the lens block 21 during imaging at preset positions 72 to 74 has shifted from the reference focus position. For example, if the focus of the lens block 21 during imaging is within the "Focus Range," it can be determined that the focus of the lens block 21 during imaging is "Focus," that is, has not shifted from the reference focus position. The "Focus Range" is measured in millimeters (mm). For example, if a change in focus when the camera unit 20 focuses on an entering or leaving vehicle (not shown) passing through gates 62 to 64 is not considered to be an interference with imaging, the "Focus Range" may be set to a wide range. By setting the "Focus Range" to a wide range, even if the focus of the lens block 21 shifts to the position of an entering or leaving vehicle during image capture at each of the preset positions 72 to 74, it is possible to prevent this shift from being determined as an image capture interference. As shown in FIG. 3 , at preset position 74, the "Focus," i.e., the reference focus position, is 80 mm. For example, if the focus of the lens block 21 during image capture changes to 70 mm due to a vehicle entering or leaving gate 64, the focus of the lens block 21 during image capture is not determined to have shifted from the reference focus position because 70 mm is within the "Focus Range." For example, if the "Focus Range" is set to a range that does not include the focus when the camera unit 20 is covered with a cloth, the change in focus of the lens block 21 during image capture due to the cloth being covered can be determined to be a change from the reference focus position, and image capture interference can be detected.

[0022] As shown in FIG. 1 , the controller 30 includes a general-purpose microcontroller 310 and a storage device 320. The storage device 320 can be configured, for example, by a solid-state drive (SSD) or a hard disk drive (HDD). The microcontroller 310 includes a central processing unit (CPU) and memory. The memory includes a read-only memory (ROM) and a random-access memory (RAM). The microcontroller 310 can virtually configure multiple information processing circuits by, for example, having the CPU execute a program stored in the memory. The multiple information processing circuits can configure the input / output unit and arithmetic unit of the microcontroller 310.

[0023] The input / output unit can, for example, acquire an image signal output by the imaging unit 24. The input / output unit can, for example, output an image signal when the camera unit 20 captures an image at an imaging position including preset positions 72 to 74 to a display (not shown). The calculation unit can constitute an imaging position switching unit 311, an autofocus processing unit 312, a focus position determination unit 313, a detection unit 314, and a notification unit 315 (described later) of the microcontroller 310. The imaging tampering detection device 100 of the first embodiment can be configured to include the detection unit 314, and may also be configured to further include the notification unit 315.

[0024] In this embodiment, an example is shown in which multiple information processing circuits built in the microcontroller 310 are realized by software. Of course, it is also possible to configure the information processing circuits by providing dedicated hardware for executing the information processing of each of the input / output unit and the arithmetic unit. Alternatively, the multiple information processing circuits may be configured by individual hardware. Dedicated hardware includes devices such as application specific integrated circuits (ASICs) and conventional circuit components arranged to perform the functions of the input / output unit and the arithmetic unit.

[0025] The shooting position switching unit 311 switches the shooting position of the camera unit 20. When performing patrol shooting with the camera unit 20, the shooting position switching unit 311 sequentially switches the camera unit 20 to an orientation and zoom magnification corresponding to each of the "Pan," "Tilt," and "Zoom" parameters of the preset positions 72 to 74 stored in the storage device 320. When the user uses the camera unit 20 to shoot an arbitrary position desired by the user, the shooting position switching unit 311 switches the camera unit 20 to an orientation and zoom magnification corresponding to the user's operation. The shooting position can be switched by operating the tilt mechanism and pan mechanism (not shown) of the camera unit 20 and the zoom adjustment unit 22. When performing patrol shooting, the shooting position can be switched, for example, at regular intervals.

[0026] For example, when the shooting position of the camera unit 20 is switched by patrol shooting or a user operation, the autofocus processing unit 312 causes the camera unit 20 to perform an autofocus operation. The autofocus processing unit 312 also causes the camera unit 20 to perform an autofocus operation when instructed by the detection unit 314, which will be described later, even when the shooting position of the camera unit 20 is not switched. The cases when the detection unit 314 instructs the execution of the autofocus operation will be described later.

[0027] The autofocus processing unit 312 may perform contrast autofocus processing that is performed by image processing, or may perform phase difference autofocus processing that does not require image processing.

[0028] In contrast autofocus processing, the autofocus processing unit 312 uses the zoom adjustment unit 22 and focus adjustment unit 23 to individually move each lens in the lens group of the lens block 21 along its optical axis. While moving each lens in the lens block 21, the autofocus processing unit 312 calculates the sharpness (contrast) of the image signal input from the imaging unit 24 and searches for a position where the calculated sharpness is maximized. Image sharpness is a physical quantity related to the clarity and sharpness of an image, and is also called sharpness. For example, the clarity of the rising edge of the black and white boundary in an image and the clarity of perspective in an image are related to image sharpness. Image sharpness can be calculated, for example, using the modulated transfer function (MTF) of the lens block 21. The transfer function (MTF) of the lens block 21 can be measured, for example, from an image captured by the camera unit 20 of a sine wave chart whose light transmittance varies in a sine curve from 100% to 0%. The greater the blur of the image, the lower the image sharpness. The blurring of the image becomes more noticeable as the deviation of the focus of the lens block 21 from the position of the subject increases.

[0029] In contrast autofocus processing, the autofocus processing unit 312 stops the movement of each lens at the position where the sharpness of the image signal is greatest, thereby completing the autofocus operation of the camera unit 20. When the autofocus operation is completed, the focal point of the lens block 21 is the position of the subject focused during shooting at the shooting position or a position near the subject.

[0030] In the case of phase-difference autofocus processing, the autofocus processing unit 312 detects the phase difference between two images formed on the imaging unit 24 by light passing through the lens block 21. The two images for which the phase difference is detected may be two images formed on separate imaging elements of the imaging unit 24 by splitting light passing through the lens block 21 into two using a beam splitter. The two images for which the phase difference is detected may also be two images formed on an autofocus (AF) sensor located on a single imaging element of the imaging unit 24 by splitting light passing through the lens block 21 using a separator lens (not shown). In the latter case, the phase difference between the two images is the image plane phase difference calculated from the output of the AF sensor. The autofocus processing unit 312 detects pixel misalignment between the two images based on the detected phase difference and, from the detected pixel misalignment, determines the amount and direction of focus misalignment of the lens block 21. The autofocus processing unit 312 executes the autofocus operation of the camera unit 20 based on the detected amount of focus misalignment.

[0031] The autofocus processing unit 312 normally terminates the autofocus operation if the autofocus operation is completed within a predetermined time from the start of the autofocus operation, and abnormally terminates the autofocus operation if the autofocus operation is not completed within the predetermined time from the start of the autofocus operation.

[0032] The focus position determination unit 313 determines the focal position of the lens block 21 when the autofocus operation has been completed successfully from the amount of movement of each lens in the lens block 21. The focus position determination unit 313 may store the determined focal position of the lens block 21 in, for example, the memory of the microcontroller 310 as the focal position after the autofocus operation. The focus position determination unit 313 can determine whether the determined focal position of the lens block 21 has deviated to either the near or far side from the reference focal positions of the preset positions 72 to 74, which are the shooting positions during the autofocus operation.

[0033] During operation of the photography tampering detection device 100, the sharpness of the image captured by the camera unit 20 is calculated to detect photography tampering by the camera unit 20. The sharpness of the image captured by the camera unit 20 can be calculated from the image signal input from the imaging unit 24. The sharpness of the image captured may be calculated continuously while the photography tampering detection device 100 is operating, or may be calculated each time the photography position of the camera unit 20 is changed. The autofocus processing unit 312, which performs contrast autofocus processing, can reuse the sharpness of the image captured for autofocus operation to detect photography tampering by the camera unit 20. In this case, no new image processing is required for tampering detection, which not only simplifies the processing procedure but also eliminates the need for a new image processing block. If the autofocus processing unit 312 does not calculate the sharpness, the detection unit 314 may calculate the sharpness of the image captured.

[0034] The detection unit 314 compares the sharpness of the image captured by the camera unit 20 with a predetermined reference sharpness. When the autofocus processing unit 312 calculates the sharpness, the detection unit 314 compares the sharpness acquired from the autofocus processing unit 312 with the reference sharpness. The reference sharpness may be a single, uniform value regardless of the shooting position of the camera unit 20, or, for example, a separate value may be set for each of the preset positions 72 to 74. In the latter case, for example, the sharpness calculated by the autofocus processing unit 312 when the lens block 21 is focused on the gates 62 to 64 corresponding to each of the preset positions 72 to 74 can be registered as the reference sharpness for each of the preset positions 72 to 74. In the storage device 320 in which the parameters of the shooting information for the preset positions 72 to 74 are registered, a "Sharpness" parameter is initially set as the reference sharpness, as shown in FIG. 3 , for example. The initially set "Sharpness" parameter can be the sharpness value of the image captured by the camera unit 20 calculated by the autofocus processing unit 312 or the detection unit 314 when the lens block 21 is focused on each of the gates 62 to 64. As shown in the example in FIG. 3, a "Sharpness Range" may be added to the shooting information for the preset positions 72 to 74. The sharpness of the captured image may be slightly shifted due to changes in the shooting conditions, such as vibration of the camera unit 20 and lighting. The "Sharpness Range" indicates the allowable range of deviation from the initially set "Sharpness" value. The reference sharpness may be stored in the storage device 320, for example.

[0035] When a predetermined change occurs in the calculated sharpness of the image captured by the camera unit 20 relative to the reference sharpness, the detection unit 314 outputs a first detection signal and instructs the autofocus processing unit 312 to perform an autofocus operation. The first detection signal is a signal indicating that a predetermined change in sharpness relative to the reference sharpness has been detected in the image captured by the camera unit 20 at the preset positions 72 to 74. The predetermined change relative to the reference sharpness includes a case where the calculated sharpness has decreased by more than a predetermined amount from the reference sharpness and a case where the calculated sharpness has changed beyond the allowable range of the reference sharpness. These cases may also include a case where the sharpness of the image captured at a preset position has changed by more than a predetermined amount from the predetermined reference sharpness for the preset position. For example, when the focus of the lens block 21 deviates by more than a certain distance from the in-focus position, the calculated sharpness decreases by more than a predetermined amount from the reference sharpness. A change in sharpness that exceeds the allowable range of the reference sharpness not only includes a decrease in sharpness beyond the lower limit of the allowable range, but also an increase in sharpness beyond the upper limit of the allowable range. An increase in sharpness occurs when the focal point of the lens block 21 approaches the in-focus position, so it is not generally considered to be a problem. However, an extreme increase in sharpness that exceeds the upper limit of the allowable range may be caused by factors other than the focal point of the lens block 21 approaching the in-focus position. The detection unit 314 can also detect an extremely high sharpness for some reason as a predetermined change from the reference sharpness.

[0036] The reference sharpness may be, for example, a uniform single value regardless of the shooting position of the camera unit 20. If the shooting positions of the camera unit 20 are preset positions 72 to 74, a reference sharpness may be set for each of the preset positions 72 to 74. When a reference sharpness is set for each of the preset positions 72 to 74, the detection unit 314 may detect that a predetermined change has occurred in the sharpness of the captured image relative to the reference sharpness of the preset positions 72 to 74 corresponding to the shooting position.

[0037] After the autofocus processing unit 312 performs an autofocus operation in response to an instruction from the detection unit 314, the focus position determination unit 313 determines whether the focus of the lens block 21 has deviated from the reference focus position of the preset positions 72 to 74, which are the shooting positions. The focus position determination unit 313 may determine whether the focus of the lens block 21 after the autofocus operation has deviated from the reference focus position using the upper and lower limit values ​​of the "Focus Range" of the preset positions 72 to 74 in FIG. 3 as thresholds. The detection unit 314 outputs a second detection signal when the focus position determination unit 313 determines that the focus of the lens block 21 after the autofocus operation has deviated from the reference focus position. The second detection signal is a signal indicating the detection of an abnormality in the autofocus operation. For example, if the shooting position at the time the first and second detection signals are output is preset position 72, the first and second detection signals output by the detection unit 314 will be detection signals related to preset position 72.

[0038] The detection unit 314 may be configured to output a second detection signal only when the focus position determination unit 313 determines that the focus of the lens block 21 after autofocus operation has shifted to the near side, closer to the camera unit 20 than the reference focus position. After autofocus operation at preset positions 72 to 74, the focal length of the lens block 21 that has shifted to the near side from the reference focus position is shorter than the lower limit of the "Focus Range" for the preset positions 72 to 74. The detection unit 314 considers this state to be a state in which an obstruction that interferes with capturing images of the gates 62 to 64 has appeared between the camera unit 20 and the gates 62 to 64 that are originally intended to be captured during image capture at the preset positions 72 to 74. A position shifted to the near side from the reference focus position may be determined, for example, by whether the focus is closer to the camera unit 20 than the adjustable range of the focus corresponding to the registered "Zoom" parameter for the preset positions 72 to 74 that are used as the image capture positions. If the focus of the lens block 21 is within the adjustable range, the focus can be considered to be substantially within the "Focus Range" of the preset positions 72 to 74 that are used as the shooting positions.

[0039] The detection unit 314 may be configured to output different detection signals in each of the following cases: when the focus of the lens block 21 after the autofocus operation deviates from the reference focus position; when the focus deviates from the reference focus position to the near side; and when the autofocus operation terminates abnormally.

[0040] The detection state of reduced sharpness, in which the detection unit 314 outputs a first detection signal, and the detection state of an abnormality in autofocus operation, in which the detection unit 314 outputs a second detection signal, can be considered to have occurred due to interference with image capture by the camera unit 20. Based on the first detection signal and the second detection signal output by the detection unit 314, the notification unit 315 outputs a notification signal to notify the user that image capture by the camera unit 20 at the preset positions 72 to 74 has been interfered with.

[0041] Next, an example of a processing procedure executed by the photography tampering detection device 100 to detect a state in which photography by the camera unit 20 in the surveillance camera device 10 of this embodiment is being obstructed will be described with reference to FIG. 4 . The photography tampering detection device 100 repeatedly executes the processing procedure illustrated in FIG. 4 while the surveillance camera device 10 is in operation. First, the autofocus processing unit 312 or the detection unit 314 calculates the image sharpness of the image signal input from the imaging unit 24 (step S101). The detection unit 314 checks whether the calculated sharpness has changed in a predetermined manner compared to the reference sharpness (step S102). In this embodiment, a uniform reference sharpness is used to check whether the calculated sharpness has changed in a predetermined manner, regardless of the shooting position of the camera unit 20.

[0042] If the calculated sharpness does not change by a predetermined amount relative to the reference sharpness (NO in step S102), the process ends. If the calculated sharpness changes by a predetermined amount relative to the reference sharpness (YES in step S102), the detection unit 314 outputs a first detection signal indicating the detection of the predetermined change relative to the reference sharpness (step S103). Based on the first detection signal output by the detection unit 314, the notification unit 315 outputs a notification signal (step S104). This notification signal may, for example, notify the user that imaging interference has been detected based on the sharpness. After the notification unit 315 outputs the notification signal, the process proceeds to step S105.

[0043] In step S105, the detection unit 314 instructs the autofocus processing unit 312 to perform an autofocus operation of the camera unit 20. The detection unit 314 checks whether the autofocus operation performed by the autofocus processing unit 312 has completed successfully (step S106). If the autofocus operation has completed abnormally (NO in step S106), the process proceeds to step S108, which will be described later. If the autofocus operation has completed successfully (YES in step S106), the detection unit 314 checks whether the focus of the lens block 21 determined by the focus position determination unit 313 has shifted to the near side after the autofocus operation (step S107). The detection unit 314 checks whether the focus of the lens block 21 has shifted to the near side after the autofocus operation based on the reference focus positions of the preset positions 72 to 74 corresponding to the shooting positions of the camera unit 20.

[0044] The detection unit 314 may determine that the focus has shifted to the near side from the reference focus position, for example, when the focal length of the lens block 21 after the autofocus operation is shorter than the lower limit value of the "Focus Range" registered for the preset positions 72 to 74 of the shooting positions. The detection unit 314 may determine that the focus has shifted to the near side from the reference focus position, when the focal length of the lens block 21 is shorter than the lower limit value of the adjustable range of the focus corresponding to the "Zoom" parameter registered for the preset positions 72 to 74 of the shooting positions.

[0045] If the focus of the lens block 21 after the autofocus operation has not shifted to the near side from the reference focus position (NO in step S107), the series of procedures ends. If the focus after the autofocus operation has shifted to the near side from the reference focus position (YES in step S107), the process proceeds to step S108.

[0046] In step S108, the detection unit 314 outputs a second detection signal indicating the detection of an abnormality in the autofocus operation. The notification unit 315 outputs a notification signal based on the second detection signal output by the detection unit 314 (step S109). This notification signal may notify that interference with photography has been detected, for example, based on the focal position of the lens block 21 after the autofocus operation of the camera unit 20, or whether or not the autofocus operation has terminated abnormally. After the notification unit 315 outputs the notification signal, the series of procedures ends.

[0047] 5 shows an example of the relationship between possible patterns of filming interference and events that occur in each pattern in the surveillance camera device 10. In the surveillance camera device 10, scenes in which filming at preset positions 72 to 74 is interfered with include, for example, the scenes shown in the leftmost column of FIG.

[0048] Here, with regard to the image sharpness of the image signal captured by the camera unit 20, changes in image sharpness are expected in each of the following scenes: "obstruction," "half of the lens is spray-painted," and "strong light hits half of the lens." The expected changes in sharpness are, for example, a decrease in image sharpness from the reference sharpness, as shown in the second column from the left in FIG. 5 . It is expected that the image sharpness will significantly decrease from the reference sharpness in each of the following scenes: "covered with a cloth," "completely painted with a spray-paint," and "strong light hits the entire lens." In a scene where the camera orientation changes, depending on the circumstances before and after the orientation change, it is expected that the image sharpness will decrease from the reference sharpness, increase from the reference sharpness, or remain unchanged at the reference sharpness by chance.

[0049] An "obstruction" refers to an object that exists between the reference focal position of preset positions 72 to 74 and the camera unit 20 and blocks the field of view of the lens block 21 in front of the reference focal position. Figure 6 shows a state in which, when the shooting position is preset position 74, a vehicle 80 in the logistics warehouse 60 blocks part of the gate 64 from the field of view of the lens block 21. In this case, the vehicle 80 corresponds to an "obstruction" that prevents the camera unit 20 from shooting the gate 64.

[0050] When the shooting of a target such as the gates 62-64 of the preset positions 72-74 is obstructed, a decrease in the image sharpness of the image signal captured by the camera unit 20 is expected in most scenes, as shown in FIG. 5 . In this embodiment, the sharpness of the image captured by the camera unit 20 is calculated during operation of the shooting tampering detection device 100, and when the calculated sharpness decreases by a predetermined amount or more from the reference sharpness, the detection unit 314 and the notification unit 315 output a first detection signal and a notification signal of shooting tampering. The first detection signal allows the shooting tampering detection device 100 to recognize, in a control manner, not just a change in contrast of the image captured by the camera unit 20, but also a change in sharpness that could lead to shooting tampering. The shooting tampering detection device 100 can notify the user of the occurrence of shooting tampering detected based on the sharpness by outputting a notification signal based on the first detection signal.

[0051] If a value that is a predetermined amount lower than the reference sharpness is set to, for example, the boundary value between the cases where the sharpness is "significantly lowered" and "decreased" in Fig. 5, it is possible to detect the occurrence of a scene of photography interference in which the sharpness of the image is significantly lowered by comparing it with the calculated sharpness. If a value that is a predetermined amount lower than the reference sharpness is set to, for example, the boundary value between the cases where the sharpness is "decreased" and "accidentally maintained" in Fig. 5, it is possible to detect the occurrence of a scene of photography interference in which the sharpness of the image is lowered or significantly lowered by comparing it with the calculated sharpness.

[0052] When a predetermined change in the sharpness of the captured image relative to the reference sharpness, for example, a decrease of a predetermined amount or more relative to the reference sharpness, is detected, for example, a scene in which a simple change in the brightness difference of the captured image occurs that is not due to the occurrence of shooting interference will not be detected. Compared to detecting the occurrence of shooting interference based on a change in the brightness difference of the captured image, this prevents a scene in which shooting interference does not occur from being mistakenly detected as a scene in which shooting interference occurs. By detecting a change in sharpness that leads to the occurrence of shooting interference, it is possible to more accurately detect interference with shooting at preset positions 72 to 74 by camera unit 20.

[0053] In this embodiment, when the calculated sharpness falls below the reference sharpness by a predetermined amount or more, the detection unit 314 and the notification unit 315 output a first detection signal and a notification signal, respectively, and an autofocus operation is performed in the camera unit 20. After the autofocus operation, it is confirmed whether the focus of the lens block 21 has moved from the reference focus position corresponding to the preset positions 72 to 74 at the start of the autofocus operation.

[0054] Regarding the focus of the lens block 21 after the autofocus operation, in the "obstruction" scene, the focus of the lens block 21 is on the near side of the reference focus position, as shown in the rightmost column of Figure 5. The near side means the side closer to the camera unit 20 than the reference focus position. In the "moving the subject farther away" scene, the focus of the lens block 21 after the autofocus operation is on the far side of the reference focus position. The far side means the side opposite the camera unit 20 than the reference focus position.

[0055] In the scenes where "half of the lens is sprayed" and "strong light hits half of the lens," the focal point of the lens block 21 after autofocus operation is nearer or farther than the reference focal position at preset positions 72 to 74. In the scene where "the camera direction changes," the focal point of the lens block 21 after autofocus operation is nearer or farther than the reference focal position at preset positions 72 to 74. Alternatively, the autofocus operation may end abnormally because a focusable subject cannot be identified, which may make the focus of the lens block 21 after autofocus operation unpredictable. In the scenes where "a cloth is placed over the lens," "the entire lens is sprayed," and "strong light hits the entire lens," the autofocus operation may end abnormally, which may make the focus of the lens block 21 after autofocus operation unpredictable.

[0056] During autofocus operation, if the focal point of the lens block 21 moves toward the camera unit 20 from the registered reference focal position, the lens block 21 is focused on an object in front of the preset positions 72 to 74 as viewed from the camera unit 20. In this case, it is assumed that an "obstructing object" is present in a position closer to the camera unit 20 than the preset positions 72 to 74. During autofocus operation, if the autofocus operation does not end normally, it is assumed that the camera unit 20 is unable to capture a subject that can be focused on. In these situations, it is considered that the field of view of the camera unit 20 is obstructed in front of the subject or near the lens block 21.

[0057] During autofocus operation, if the focus of the lens block 21 moves to a position deviated from the reference focus position to the near side, or if the autofocus operation does not end normally, the detection unit 314 and the notification unit 315 output a second detection signal and a notification signal. The second detection signal allows the photography tampering detection device 100 to recognize, in a controlled manner, the occurrence of an abnormality in the autofocus operation that could lead to photography tampering. An abnormality in the autofocus operation includes a shift in the focus of the lens block 21 and an abnormal end of the autofocus operation. The abnormality in the autofocus operation can be detected based on the focus of the lens block 21. The photography tampering detection device 100 can notify the user of the occurrence of photography tampering detected based on the focus of the lens block 21 by outputting a notification signal based on the second detection signal. In the photography tampering detection device 100 of the first embodiment, if an abnormality in the autofocus operation is detected after outputting a notification signal based on the first detection signal indicating a decrease in the sharpness of the captured image, a notification signal based on the second detection signal indicating this is output. By outputting both a notification signal associated with a decrease in the sharpness of the captured image and a notification signal associated with an abnormality in the autofocus operation, the notification signals can notify the user of the occurrence of interference with photography with greater accuracy.

[0058] [First Modification of First Embodiment] In the photography tampering detection device 100 of the first embodiment, the detection unit 314 checks in step S107 whether the focus of the lens block 21 after autofocusing has shifted from the reference focus position to the near side. In the photography tampering detection device 100 of the first modification, the detection unit 314 checks in step S107 whether the focus of the lens block 21 after autofocusing has shifted from the reference focus position, regardless of whether it is to the near side or the far side. When checking for focus shift regardless of direction, if the focus has not shifted from the reference focus position (NO in step S107), the series of procedures ends. If the focus has shifted from the reference focus position (YES in step S107), the process proceeds to step S108. In this modification, even if the focus of the lens block 21 after autofocusing has shifted from the reference focus position to the far side, the second detection signal can be used to control the system to recognize the occurrence of an abnormality in the autofocus operation that could lead to photography tampering.

[0059] [Second Modification of the First Embodiment] In the photography tampering detection device 100 of the first embodiment and its first modification, an autofocus operation is performed after outputting a first detection signal indicating a decrease in the sharpness of an image captured by the camera unit 20 and a notification signal of photography tampering based on the sharpness. If the focus of the lens block 21 deviates from the reference focus position or the autofocus operation terminates abnormally during this autofocus operation, a second detection signal indicating an abnormality in the autofocus operation and a notification signal based on the focus of the lens block 21 are output. However, the output of the notification signal (step S104 of FIG. 4 ) after outputting the first detection signal (step S103 of FIG. 4 ) may be omitted. In this modification, in which the output of the notification signal based on the first detection signal is omitted, when a predetermined change in sharpness occurs (YES in step S102 of FIG. 4 ), the detection unit 314 outputs a first detection signal (step S103 of FIG. 4 ). After outputting the first detection signal, the detection unit 314 instructs execution of the autofocus operation (step S105 of FIG. 4 ). The detection unit 314 and the notification unit 315 execute the procedures (steps S106 to S109 in FIG. 4) after confirming the normal completion of the autofocus operation. In the first embodiment, a notification signal based on the first detection signal and a notification signal based on the second detection signal are output, respectively, but in this modified example, only a notification signal based on the second detection signal is output. In this modified example, a notification signal is output when both a change in sharpness that could lead to the occurrence of photography interference and an abnormality in the autofocus operation are detected, and the occurrence of photography interference is expected with a high probability. This increases the reliability of the notification of a photography interference state by outputting a notification signal.

[0060] [Second Embodiment] As shown in the flowchart of FIG. 7 , the second embodiment of the photography tampering detection device 100 omits all steps from step S105 onward in FIG. 4 , which were performed in the first embodiment of the photography tampering detection device 100. In this embodiment, the series of steps ends after outputting the first detection signal and the photography tampering notification signal based on the sharpness (steps S103 and S104). The second embodiment of the photography tampering detection device 100 detects a change in sharpness that could lead to photography tampering when a predetermined change occurs in sharpness relative to the reference sharpness, thereby enabling accurate detection of photography tampering. In the second embodiment of the photography tampering detection device 100, when the autofocus processing unit 312 performs contrast autofocus processing, the sharpness of the captured image calculated by the autofocus processing unit 312 for autofocus operation can be reused. The reused sharpness of the captured image can be used to detect photography tampering by the camera unit 20. In this case, the photography interference detection device 100 of the second embodiment does not need to perform new image processing for interference detection, which not only simplifies the processing procedure but also eliminates the need to provide a new image processing block.

[0061] [Third Embodiment] In the third embodiment of the photography tampering detection device 100, as shown in the flowchart of FIG. 8, processing starts when the photography position of the camera unit 20 is switched to one of the preset positions 72 to 74 (step S201). In the started processing, the detection unit 314 instructs the autofocus processing unit 312 to execute an autofocus operation of the camera unit 20 (step S202). The detection unit 314 checks whether the autofocus operation executed by the autofocus processing unit 312 was completed successfully (step S203). If the autofocus operation was not completed successfully but terminated abnormally (NO in step S203), the processing proceeds to step S205, described below. If the autofocus operation was completed successfully (YES in step S203), the detection unit 314 checks whether the focus of the lens block 21 after the autofocus operation has shifted from the reference focus position (step S204). The direction of the shift to be checked may be either the near side or the far side of the reference focus position, or the check may be limited to the near side. In step S204, the detection unit 314 checks whether the focus of the lens block 21 after the autofocus operation at the preset positions 72 to 74, which are used as the photographing positions, has deviated from the reference focus position.

[0062] If the focus of the lens block 21 after the autofocus operation has not deviated from the reference focus position (NO in step S204), the process proceeds to step S207 and subsequent steps described below. If the focus after the autofocus operation has deviated from the reference focus position (YES in step S204), the process proceeds to step S205. In step S205, the detection unit 314 outputs a second detection signal. Based on the second detection signal output by the detection unit 314, the notification unit 315 outputs a notification signal notifying the user that, for example, photography interference has been detected based on the focus of the lens block 21 (step S206). After the notification unit 315 outputs the notification signal, the process ends.

[0063] After step S207, steps S207 to S210 are executed. The processing of each step in steps S207 to S210 is the same as the processing of steps S101 to S104 in FIG. 7, which was referred to in the description of the second embodiment. In step S207, the autofocus processing unit 312 or the detection unit 314 calculates the sharpness of the image of the image signal input from the imaging unit 24. In step S202, the detection unit 314 checks whether the calculated sharpness has changed by a predetermined amount relative to the reference sharpness. If the calculated sharpness has not changed by a predetermined amount relative to the reference sharpness (NO in step S208), the series of steps ends. If the calculated sharpness has changed by a predetermined amount relative to the reference sharpness (YES in step S208), the detection unit 314 outputs a first detection signal (step S209). Based on the first detection signal output by the detection unit 314, the notification unit 315 outputs a notification signal (step S210). This notification signal may, for example, notify the user that imaging interference has been detected based on the sharpness. After the notification unit 315 outputs the notification signal, the series of procedures ends.

[0064] The sharpness of the image captured by the camera unit 20 varies depending on whether the camera unit 20 is in focus. When the camera unit 20's shooting position is switched to one of the preset positions 72 to 74, the sharpness of the image captured at the switched shooting position must be compared with a reference sharpness. In the third embodiment of the photography interference detection device 100, an autofocus operation is performed when the camera unit 20's shooting position is switched to one of the preset positions 72 to 74. Based on the focus of the lens block 21 after this autofocus operation, the occurrence of an abnormality in the autofocus operation that could lead to photography interference can be more accurately recognized in a control system. Note that after the processing procedure of FIG. 8 is executed, processing according to any of the procedures of the first embodiment, its variations, and the second embodiment described with reference to FIGS. 4 and 7 may be performed until the camera unit 20's shooting position is next switched.

[0065] In the embodiments and modifications other than the second embodiment described above, if the focus of the lens block 21 deviates from the reference focus position to the near side after the autofocus operation, the user is notified of the occurrence of "photography interference due to an obstruction." Alternatively, if the autofocus operation does not end normally, the user is notified of the occurrence of "photography interference due to failure to capture the subject." However, if the focus of the lens block 21 deviates from the reference focus position, including if the focus of the lens block 21 deviates from the reference focus position to the far side after the autofocus operation, the user may be notified that some kind of photography interference has occurred. Furthermore, different notifications may be issued in each of the following cases: if the focus of the lens block 21 deviates from the reference focus position to the near side, if the focus deviates from the reference focus position to the far side, and if the autofocus operation ends abnormally.

[0066] [Fourth Embodiment] The fourth embodiment is an embodiment in which imaging interference is detected using a change in the autofocus position. In this embodiment, the autofocus processing unit 312 performs autofocus processing that does not require image processing. The autofocus processing that does not require image processing may be, for example, phase-difference autofocus processing or laser autofocus processing. In this embodiment, a case in which phase-difference autofocus is used will be described.

[0067] In phase-difference autofocus processing, the autofocus processing unit 312 detects the phase difference between two images formed on the imaging unit 24 by light passing through the lens block 21. The two images for which the phase difference is detected may be two images formed on separate imaging elements of the imaging unit 24 by splitting light passing through the lens block 21 into two using a beam splitter. The two images for which the phase difference is detected may also be two images formed on an autofocus (AF) sensor located on a single imaging element of the imaging unit 24 by splitting light passing through the lens block 21 using a separator lens (not shown). In the latter case, the phase difference between the two images is the image plane phase difference calculated from the output of the AF sensor. The autofocus processing unit 312 detects pixel misalignment between the two images based on the detected phase difference and, from the detected pixel misalignment, determines the amount and direction of focus misalignment of the lens block 21.

[0068] The autofocus processing unit 312 executes an autofocus operation of the camera unit 20 based on the detected amount of defocus. During the autofocus operation, the autofocus processing unit 312 moves each lens of the lens block 21 in the direction of its optical axis using the zoom adjustment unit 22 and the focus adjustment unit 23 so as to eliminate the amount of defocus. The autofocus processing unit 312 stops the movement of each lens at a position where the amount of defocus has been eliminated, thereby completing the autofocus operation of the camera unit 20. When the autofocus operation is completed, the focus of the lens block 21 becomes the position of the subject that was focused during shooting at the shooting position.

[0069] The autofocus processing unit 312 normally terminates the autofocus operation if the autofocus operation is completed within a predetermined time from the start of the autofocus operation, and abnormally terminates the autofocus operation if the autofocus operation is not completed within the predetermined time from the start of the autofocus operation.

[0070] The focus position determination unit 313 determines the focal position of the lens block 21 when the autofocus operation has been completed successfully from the amount of movement of each lens in the lens block 21. The focus position determination unit 313 may store the determined focal position of the lens block 21 in, for example, the memory of the microcontroller 310 as the focal position after the autofocus operation. The focus position determination unit 313 may determine whether the determined focal position of the lens block 21 has deviated to either the near or far side from the reference focal position of the preset positions 72 to 74, which are the shooting positions during the autofocus operation. The focus position determination unit 313 may determine whether the focal position of the lens block 21 after the autofocus operation has deviated from the reference focal position using the upper and lower limit values ​​of the "Focus Range" of the preset positions 72 to 74 in FIG. 3 as thresholds. The focus position determination unit 313 may determine whether the focal position of the lens block 21 that has deviated from the reference focal position of the preset positions 72 to 74 has deviated to either the near or far side.

[0071] The detection unit 314 outputs a second detection signal indicating detection of interference with photography when the focus position determination unit 313 determines that the focus of the lens block 21 after autofocus operation when the photography position is switched to one of the preset positions 72 to 74 has deviated from the reference focus position. The second detection signal is also simply referred to as a detection signal. The detection unit 314 may output the detection signal based on the determination result of whether the position deviated from the reference focus position of the preset positions 72 to 74 is closer to the lens block 21 or farther from the lens block 21 than the reference focus position.

[0072] The detection unit 314 may be configured to output a second detection signal only when the focus position determination unit 313 determines that the focus of the lens block 21 after autofocus operation has shifted to the near side, closer to the camera unit 20 than the reference focus position. After autofocus operation at preset positions 72 to 74, the focal length of the lens block 21 that has shifted to the near side from the reference focus position is shorter than the lower limit of the "Focus Range" for the preset positions 72 to 74. The detection unit 314 considers this state to be a state in which an obstruction that interferes with capturing images of the gates 62 to 64 has appeared between the camera unit 20 and the gates 62 to 64 that are originally intended to be captured during image capture at the preset positions 72 to 74. A position shifted to the near side from the reference focus position may be determined, for example, by whether the focus is closer to the camera unit 20 than the adjustable range of the focus corresponding to the registered "Zoom" parameter for the preset positions 72 to 74 that are used as the image capture positions. If the focus of the lens block 21 is within the adjustable range, the focus can be considered to be substantially within the "Focus Range" of the preset positions 72 to 74 that are used as the shooting positions.

[0073] The detection unit 314 may be configured to output a second detection signal only when the focus of the lens block 21 after the autofocus operation deviates from the reference focus position of the subject to be photographed during autofocus, for example, only when the autofocus operation terminates abnormally. The detection unit 314 may be configured to output different detection signals in each of the following cases: when the focus of the lens block 21 after the autofocus operation deviates from the reference focus position, when the focus deviates from the reference focus position to the near side, and when the autofocus operation terminates abnormally.

[0074] Based on the detection signal output by the detection unit 314, the notification unit 315 outputs a notification signal to notify the user that photography by the camera units 20 at the preset positions 72 to 74 has been obstructed.

[0075] Next, an example of a processing procedure executed by the photography interference detection device 100 to detect a state in which photography at preset positions 72 to 74 by the camera unit 20 in the surveillance camera device 10 of this embodiment is interfered with will be described with reference to Figure 9. The photography interference detection device 100 repeatedly executes the processing procedure illustrated in Figure 9 while the surveillance camera device 10 is in operation. The processing procedure in Figure 9 is an example of detecting photography interference when the focus of the lens block 21 after an autofocus operation shifts to the near side from the reference focus position.

[0076] First, when the shooting position of the camera unit 20 is switched to one of the preset positions 72 to 74 (step S301), the detection unit 314 instructs the autofocus processing unit 312 to execute an autofocus operation of the camera unit 20 (step S302). The detection unit 314 checks whether the autofocus operation executed by the autofocus processing unit 312 was completed successfully (step S303). If the autofocus operation was not completed successfully but terminated abnormally (NO in step S303), the process proceeds to step S305 (described below). If the autofocus operation was completed successfully (YES in step S303), the detection unit 314 checks whether the focus of the lens block 21 determined by the focus position determination unit 313 has shifted to the near side after the autofocus operation (step S304). The detection unit 314 checks whether the focus of the lens block 21 has shifted to the near side after the autofocus operation based on the reference focus position of the preset positions 72 to 74 corresponding to the shooting positions of the camera unit 20.

[0077] The detection unit 314 may determine that the focus has shifted to the near side from the reference focus position, for example, when the focal length of the lens block 21 after the autofocus operation is shorter than the lower limit value of the "Focus Range" registered for the preset positions 72 to 74 of the shooting positions. The detection unit 314 may determine that the focus has shifted to the near side from the reference focus position, when the focal length of the lens block 21 is shorter than the lower limit value of the adjustable range of the focus corresponding to the "Zoom" parameter registered for the preset positions 72 to 74 of the shooting positions.

[0078] If the focus of the lens block 21 after the autofocus operation has not shifted to the near side from the reference focus position (NO in step S304), the series of procedures ends. If the focus after the autofocus operation has shifted to the near side from the reference focus position (YES in step S304), the process proceeds to step S305.

[0079] In step S305, the detection unit 314 outputs a detection signal. The notification unit 315 outputs a notification signal based on the detection signal output by the detection unit 314 (step S306). After the notification unit 315 outputs the notification signal, the series of procedures ends.

[0080] 5 shows an example of the relationship between possible patterns of filming interference and events that occur in each pattern in the surveillance camera device 10. In the surveillance camera device 10, scenes in which filming at preset positions 72 to 74 is interfered with include, for example, the scenes shown in the leftmost column of FIG.

[0081] Of these, in the "obstruction" scene, as shown in the rightmost column of FIG. 5, the focal point of the lens block 21 is on the near side of the reference focal position of the preset positions 72 to 74. The near side means the side closer to the camera unit 20 than the reference focal position. In the "moving the subject farther away" scene, the focal point of the lens block 21 after the autofocus operation is on the far side of the reference focal position. The far side means the side opposite the camera unit 20 than the reference focal position.

[0082] In the scenes where "half of the lens is sprayed" and "strong light hits half of the lens," the focal point of the lens block 21 after autofocus operation is nearer or farther than the reference focal position of the preset positions 72 to 74. In the scene where "the camera direction changes," the focal point of the lens block 21 after autofocus operation is nearer or farther than the reference focal position of the preset positions 72 to 74. Alternatively, the autofocus operation may end abnormally because a focusable subject cannot be identified, which may make the focus of the lens block 21 after autofocus operation unpredictable. In the scenes where "a cloth is placed over the lens," "the entire lens is sprayed," and "strong light hits the entire lens," the autofocus operation may end abnormally, which may make the focus of the lens block 21 after autofocus operation unpredictable.

[0083] An "obstruction" refers to an object that exists between the reference focal position of preset positions 72 to 74 and the camera unit 20 and blocks the field of view of the lens block 21 in front of the reference focal position. Figure 6 shows a state in which, when the shooting position is preset position 74, a vehicle 80 in the logistics warehouse 60 blocks part of the gate 64 from the field of view of the lens block 21. In this case, the vehicle 80 corresponds to an "obstruction" that prevents the camera unit 20 from shooting the gate 64.

[0084] If shooting of a subject such as gates 62 to 64 of preset positions 72 to 74 is obstructed, it is expected that the focus of lens block 21 after autofocus operation will deviate from the reference focus position. For example, in a scene where shooting of a subject is obstructed by an "obstruction," it is expected that the focus of lens block 21 after autofocus operation will move toward camera unit 20 from the reference focus position, as shown in FIG.

[0085] In this embodiment, after the autofocus operation when the shooting position of the camera unit 20 switches to one of the preset positions 72 to 74, the detection unit 314 detects the focus of the lens block 21. This autofocus operation is essentially performed as an operation in place of detecting the position of the object to be shot, to confirm, through the focus of the lens block 21, whether the object being shot by the camera unit 20 has changed to an object closer to the camera unit 20 than the gates 62 to 64. During the autofocus operation, if the focus of the lens block 21 moves closer to the near side than the registered reference focus position, the focus of the lens block 21 is adjusted to an object located in front of the gates 62 to 64 of the preset positions 72 to 74. In this case, it is estimated that the shooting of the gates 62 to 64 that were originally intended to be shot has been obstructed, and the gates 62 to 64 have not been properly shot by the camera unit 20.

[0086] During autofocus operation, when the focal point of the lens block 21 moves to a position away from the reference focal position, the detection unit 314 and the notification unit 315 output a second detection signal and a notification signal. The detection signal allows the photography tampering detection device 100 to recognize the occurrence of photography tampering in a control manner. The photography tampering detection device 100 can notify the user of the occurrence of photography tampering by the notification signal.

[0087] In this embodiment, if the focal point of the lens block 21 moves closer to the reference focal position after autofocusing at preset positions 72 to 74, the lens block 21 is focused on an object in front of gates 62 to 64. In this case, it is assumed that an "obstructing object" is present on the camera unit 20 side of gates 62 to 64, which are the subject of photography. If the autofocusing operation does not end normally, it is assumed that the lens block 21 has not captured the subject of photography to be focused on. In these cases, it is assumed that the field of view of the camera unit 20 is obstructed in front of the reference focal position or near the lens block 21.

[0088] During autofocus operation, when the focal point of the lens block 21 moves to a position deviated from the reference focal position to the near side, the detection unit 314 and the notification unit 315 output a detection signal and a notification signal indicating that photography interference has occurred due to an "obstruction." The photography interference detection device 100 can recognize the occurrence of photography interference due to an "obstruction" through the detection signal. The photography interference detection device 100 can notify the user of the occurrence of photography interference due to an "obstruction" through the notification signal.

[0089] In this embodiment, if the autofocus operation at preset positions 72 to 74 does not end normally, the detection unit 314 and the notification unit 315 output a second detection signal and a notification signal. The detection signal allows the photography tampering detection device 100 to recognize, in a control manner, the occurrence of photography tampering caused by the lens block 21 not capturing the subject to be focused on. The photography tampering detection device 100 can notify the user, by the notification signal, of the occurrence of photography tampering caused by the lens block 21 not capturing the subject to be focused on.

[0090] In this embodiment, if the focus of the lens block 21 deviates from the reference focus position to the near side after the autofocus operation, the user is notified that "photography interference due to an obstruction" has occurred. Alternatively, if the autofocus operation does not end normally, the user is notified that "photography interference due to failure to capture the subject" has occurred. However, if the focus of the lens block 21 deviates from the reference focus position, including if the focus of the lens block 21 deviates from the reference focus position to the far side after the autofocus operation, the user may be notified that some kind of photography interference has occurred. Furthermore, different notifications may be issued in each of the following cases: if the focus of the lens block 21 deviates from the reference focus position to the near side, if the focus deviates from the reference focus position to the far side, and if the autofocus operation ends abnormally.

[0091] In this embodiment, the autofocus operation of the camera unit 20 is performed using phase-difference autofocus processing, which does not require image processing, so the detection unit 314 can quickly detect the occurrence of photography tampering from the relationship between the focus after the autofocus operation and the reference focus position. In the photography tampering detection device 100 of this embodiment, the time it takes for the detection unit 314 to detect photography tampering can be reduced.

[0092] In the above embodiments and variants, the photography interference detection device 100 is provided in the controller 30, but the photography interference detection device of the present invention may also be provided in a part other than the controller 30, such as a computer that communicates with the controller 30 via a network.

[0093] Although the embodiments and modifications of the present invention have been described above, the embodiments can be modified or modified based on the above disclosure. All components of the above embodiments and modifications, and all features described in the claims, may be individually extracted and combined, unless they contradict each other.

[0094] According to this embodiment, it is possible to provide a photography tampering detection device and a photography tampering detection method that can accurately detect tampering with photography by a surveillance camera.

Claims

1. A photography tampering detection device for detecting photography tampering of a camera, comprising a detection unit which outputs a first detection signal indicating detection of a change in sharpness of an image captured by the camera at a preset position when it detects that the sharpness of the image captured by the camera has changed by a predetermined amount or more from a predetermined standard sharpness of the preset position.

2. The photography tampering detection device of claim 1, wherein the detection unit outputs a second detection signal indicating detection of an abnormality in the autofocus operation when the sharpness of the image captured by the camera at the preset position changes from the reference sharpness by more than the specified amount and the focus after autofocus operation of the camera deviates from the reference focus position of the preset position.

3. The photography tampering detection device of claim 1, wherein the detection unit outputs a second detection signal indicating detection of an abnormality in the autofocus operation when the sharpness of the image captured by the camera at the preset position changes from the reference sharpness by more than the specified amount and the autofocus operation of the camera is not completed within a specified time from the start of the autofocus operation and terminates abnormally.

4. A photography tampering detection device for detecting photography tampering of a camera, comprising a detection unit that outputs a detection signal indicating detection of photography tampering of the preset position when the focus of the camera after autofocus operation deviates from the reference focus position of the preset position.

5. The photography tampering detection device of claim 4, wherein the detection unit outputs the detection signal when it detects that the autofocus operation has not been completed within a predetermined time from the start of the autofocus operation and has abnormally terminated.

6. A method for detecting interference with camera photography, comprising the steps of: when it is detected that the sharpness of an image captured by the camera has changed by a predetermined amount or more from a predetermined reference sharpness of a preset position, outputting a first detection signal indicating detection of a change in sharpness of the image captured by the camera at the preset position.

7. A method for detecting interference with a camera's photography, comprising the steps of: when the focus of the camera after autofocus operation deviates from a reference focus position of a preset position, outputting a detection signal indicating detection of interference with photography at the preset position.

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