Photographing interference detection device

Abstract

To achieve more accurate detection in interference of photographing of a monitoring place by a camera.SOLUTION: A photographing interference detection device 100 that detects photographing interference of a camera unit 20, comprises a detection part 314 that is provided to a calculation part of a microcontroller 310. The detection part 314 outputs a first detection signal in the case where a sharpness of a photographing image photographed by the camera unit 20 in preset positions 72 to 74 that are previously registered is changed from a preset reference sharpness of the preset positions 72 to 74 by a predetermined amount or larger. The first detection signal indicates detection of sharpness deterioration of a photographing image of the camera unit 20 in the preset positions 72 to 74. The detection part 314 further outputs a second detection signal indicating abnormal detection of an auto focus operation when a focus point of a lens block 21 of the camera unit after the auto focus operation is deviated from a reference focal position of the lens block 21.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 proposes a technique for calculating the luminance difference between an image captured by a surveillance camera and a reference image for each pixel, and determining whether or not camera tampering has occurred based on the number of changed pixels for which the luminance difference is greater than a first threshold value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-77517 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technology of Patent Document 1 may erroneously determine that camera interference has occurred, for example, when an obstacle placed over the camera lens for interference is removed, causing a change in the brightness difference between the surveillance camera image and the reference image. The present invention aims to more accurately detect interference with the camera's capture of a surveillance location. [Means for solving the problem]

[0005] In order to achieve the above object, a shooting tampering detection device according to one aspect of the present invention comprises: A device for detecting camera tampering, comprising: The camera includes a detection unit that outputs a first detection signal indicating detection of a change in sharpness of an image captured by the camera at a pre-registered preset position when it detects that the sharpness of the image captured by the camera at the pre-registered preset position has changed by a predetermined amount or more from a predetermined reference sharpness of the pre-registered preset position. Effect of the Invention

[0006] According to the present invention, it is possible to more accurately detect interference with the photography of a monitored location by a camera. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an outline of the configuration of a surveillance camera device equipped with a shooting tampering detection device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an example of setting of preset positions by the camera unit of FIG. [Diagram 3] FIG. 3 is a diagram showing shooting information registered for the preset positions in FIG. [Figure 4] FIG. 4 is a flowchart illustrating an example of a processing procedure executed in the photography tampering detection device of FIG. [Diagram 5] FIG. 5 is a diagram showing an example of the relationship between possible patterns of imaging interference in the surveillance camera device of FIG. 1 and events occurring in each pattern. [Figure 6] FIG. 6 is a diagram showing an example of a state in which one of the preset positions in FIG. 2 is blocked from the field of view of the lens block by an obstruction. [Figure 7] FIG. 7 is a flowchart showing an example of a processing procedure executed in the shooting sabotage detection device according to the second embodiment of the present invention. [Figure 8] FIG. 8 is a flowchart showing an example of a processing procedure executed in a shooting sabotage detection device according to the third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention 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.

[0009] The following embodiments are examples of devices and the like for embodying the technical idea of ​​the present invention. The technical idea of ​​the present invention does not limit the materials, shapes, structures, arrangements, etc. of each component part to those described below.

[0010] [First embodiment] 1, a photography tampering detection device 100 of the first embodiment is provided in a surveillance camera device 10 that outputs a photographed image 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 can be configured using, for example, the controller 30.

[0011] The camera unit 20 is installed, for example, at a high place in the monitored space. The high place may be, for example, the ceiling of the monitored space. The camera unit 20 may be, for example, a PTZ (Pan-Tilt-Zoom) camera with a built-in tilt mechanism and pan mechanism (neither shown) that change the shooting direction up, down, left, and right. The camera unit 20 has a lens block 21, a zoom adjustment unit 22, a focus adjustment unit 23, and an imaging unit 24.

[0012] The lens block 21 has a lens group made up of a plurality of lenses. Each lens constituting the lens group can move in the direction of its respective lens optical axis. The zoom adjustment unit 22 and the focus adjustment unit 23 move each lens of the lens group individually 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.

[0013] The imaging unit 24 is an image sensor having a solid-state imaging element. For example, a CMOS (Complementary Metal-Oxide-Semiconductor) or a CCD (Charge-Coupled Device) can be used as the solid-state imaging element. An image is formed on the imaging unit 24 by light passing 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.

[0014] The camera unit 20 can perform patrol photography by sequentially switching the photographing position among a plurality of preset positions. In addition to patrol photography, the camera unit 20 can perform photography at any position desired by the user, for example, by operating an operation panel (not shown). After photographing an arbitrary position with the camera unit 20 by the user's operation, if the original photographing position is registered as a preset position, the photographing position of the camera unit 20 can be returned to the original position. The preset positions of the camera unit 20 can be registered in advance. FIG. 2 shows a case where three gates 62 to 64 provided on a wall 61 of a logistics warehouse 60, which is a monitored space, are set as preset positions 72 to 74. In this example, the camera unit 20 is installed on the ceiling 65 of the logistics warehouse 60.

[0015] 3 shows shooting information by the camera unit 20 that is registered in advance for each of the preset positions 72 to 74. The shooting information of the registered preset positions 72 to 74 can be stored, for example, in a storage device 320 (described later) of the controller 30. For example, when the camera unit 20 is a PTZ camera, parameters of "Pan," "Tilt," and "Zoom" are registered in the storage device 320 as the shooting information of the preset positions 72 to 74.

[0016] "Pan" is the left / right swing angle of camera unit 20 from a reference direction (not shown), "Tilt" is the up / down swing angle of camera unit 20 from the reference direction, both in degrees. "Zoom" is the optical zoom magnification of the subject by zoom lens 211.

[0017] The "Focus" parameter is initially set for each of the preset positions 72 to 74 in which the "Pan", "Tilt", and "Zoom" parameters are registered as shooting information. "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 lens when the lens block 21 is replaced with an optically equivalent lens. In the initial setting of the "Focus" parameter, the camera unit 20 photographs each of the preset positions 72 to 74 with the registered "Pan", "Tilt", and "Zoom" parameters, and performs an autofocus operation. When photographing each of the preset positions 72 to 74 in the state shown in FIG. 2 in order to set the "Focus" parameter, the lens block 21 focuses on each of the gates 62 to 64 by the autofocus operation performed by the camera unit 20. The focus of the lens block 21 at this time is an initial setting value in the shooting information of each of the preset positions 72 to 74, that is, a reference focus position, and is registered in the storage device 320 as "Focus" together with the parameters of "Pan", "Tilt", and "Zoom". The registered reference focus positions ("Focus") of each of the preset positions 72 to 74 can be used, for example, to detect shooting interference with the surveillance camera device 10. Shooting interference with the surveillance camera device 10 can be detected, for example, based on whether the focus of the lens block 21 during shooting at each of the preset positions 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 the autofocus operation with "Focus", that is, the reference focus position, during shooting at each of the preset positions 72 to 74. The position of the focus is also called the focus position.

[0018] In the example shown in FIG. 3, "Focus Range" is added to the shooting information of the preset positions 72 to 74. The focus of the lens block 21 may shift slightly due to, for example, vibration of the camera unit 20, changes in shooting conditions such as lighting, even if the object to be shot by the camera unit 20 does not change. "Focus Range" indicates the allowable range of the focus shift of the lens block 21 from the reference focus position when determining whether the focus of the lens block 21 at the time of shooting the preset positions 72 to 74 has changed from the reference focus position. For example, if the focus of the lens block 21 at the time of shooting is within the range of "Focus Range", it can be determined that the focus of the lens block 21 at the time of shooting is "Focus", that is, has not changed from the reference focus position. The unit of "Focus Range" is millimeters (mm). For example, if the change in focus when the camera unit 20 focuses on an entering / leaving vehicle (not shown) passing through the gates 62 to 64 is not considered to be an obstruction to shooting, 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 at the time of photographing at each of the preset positions 72 to 74 shifts to the position of an entering or leaving vehicle, it is possible to prevent the shift from being determined as a photographing obstruction. As shown in FIG. 3, at the preset position 74, the "Focus", i.e., the reference focus position, is 80 (mm). For example, if the focus of the lens block 21 at the time of photographing changes to 70 (mm) due to a vehicle entering or leaving the gate 64, since 70 (mm) is within the "Focus Range", it is not determined that the focus of the lens block 21 at the time of photographing has changed from the reference focus position. 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, for example, the change in focus of the lens block 21 at the time of photographing due to the cloth being covered can be determined to be a change from the reference focus position, and photographing obstruction can be detected.

[0019] As shown in FIG. 1, the controller 30 has a general-purpose microcontroller 310 and a storage device 320. The storage device 320 can be configured, for example, by an SSD (Solid State Drive) or an HDD (Hard Disk Drive). The microcontroller 310 includes a CPU (Central Processing Unit) and a memory. The memory includes a ROM (Read Only Memory) and a RAM (Random Access Memory). The microcontroller 310 can virtually configure a plurality of information processing circuits by, for example, executing a program stored in the memory by the CPU. The plurality of information processing circuits can configure an input / output unit and an arithmetic unit of the microcontroller 310.

[0020] The input / output unit can acquire, for example, an image signal output by the imaging unit 24. The input / output unit can output, for example, an image signal when the camera unit 20 captures an image at a shooting position including the preset positions 72 to 74 to a display (not shown). The calculation unit can configure a shooting target switching unit 311, an autofocus processing unit 312, a focus position determination unit 313, a detection unit 314, and a notification unit 315, which will be described later, of the microcontroller 310. The shooting interference detection device 100 according to this embodiment can be configured to include the detection unit 314, and may further include the notification unit 315.

[0021] 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 prepare dedicated hardware for executing each information processing of the input / output unit and the arithmetic unit to configure the information processing circuits. Also, the multiple information processing circuits may be configured by individual hardware. The dedicated hardware includes devices such as application specific integrated circuits (ASICs) and conventional circuit components arranged to execute the functions of the input / output unit and the arithmetic unit.

[0022] The photographing position switching unit 311 switches the photographing position of the camera unit 20. When the photographing position switching unit 311 performs patrol photographing with the camera unit 20, the photographing position switching unit 311 sequentially switches the camera unit 20 to the orientation and zoom magnification corresponding to each parameter of "Pan", "Tilt", and "Zoom" of the preset positions 72 to 74 stored in the storage device 320. When the photographing position switching unit 311 photographs an arbitrary position desired by the user with the camera unit 20, the photographing position switching unit 311 switches the camera unit 20 to the orientation and zoom magnification corresponding to the user's operation. The photographing position can be switched by operating a tilt mechanism and a pan mechanism (not shown) of the camera unit 20 and the zoom adjustment unit 22. When patrol photographing is performed, the photographing position can be switched at regular intervals, for example.

[0023] The autofocus processing unit 312 executes the autofocus operation of the camera unit 20, 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 executes the autofocus operation of the camera unit 20 even when the shooting position of the camera unit 20 is not switched, for example, when instructed by the detection unit 314 described later. The cases when the execution of the autofocus operation is instructed by the detection unit 314 will be described later.

[0024] 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.

[0025] In contrast autofocus processing, the autofocus processing unit 312 moves each lens of the lens group of the lens block 21 individually in the direction of the optical axis of each lens by the zoom adjustment unit 22 and the focus adjustment unit 23. While moving each lens of 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 large. The sharpness of an image is a physical quantity related to the clarity and sharpness of an image, and is also called sharpness. For example, the clarity of the rise of the boundary between white and black in an image and the clarity of the perspective of an image are related to the sharpness of an image. The sharpness of an image can be calculated, for example, using the transfer function (modulated transfer function) 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 that captures a sine wave chart in which the light transmittance changes in a sine curve from 100% to 0%. The sharpness of an image decreases as the image becomes more blurred. The greater the deviation of the focus of lens block 21 from the position of the subject, the more noticeable the blurring of the image becomes.

[0026] In contrast autofocus processing, autofocus processing unit 312 stops the movement of each lens at the position where the sharpness of the image signal is maximized, and completes the autofocus operation of camera unit 20. When the autofocus operation is completed, the focal point of lens block 21 becomes the position of the subject focused during shooting at the shooting position or a position near the subject.

[0027] 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 the light passing through the lens block 21 into two by a beam splitter. The two images for which the phase difference is detected may be two images formed on an AF (Auto Focus) sensor arranged on a single imaging element of the imaging unit 24 by splitting the light passing through the lens block 21 into two by a separator lens (not shown). In the latter case, the phase difference between the two images is an image plane phase difference obtained from the output of the AF sensor. The autofocus processing unit 312 detects pixel shift between the two images based on the detected phase difference, and detects the amount and direction of focus shift of the lens block 21 from the detected pixel shift. The autofocus processing unit 312 executes the autofocus operation of the camera unit 20 based on the detected amount of focus shift.

[0028] The autofocus processing unit 312 normally ends the autofocus operation if the autofocus operation is completed within a predetermined time from the start of the autofocus operation, and abnormally ends the autofocus operation if the autofocus operation is not completed within a predetermined time from the start of the autofocus operation.

[0029] The focus position determination unit 313 determines the focal position of the lens block 21 when the autofocus operation is normally completed from the movement amount of each lens of 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 near or far from the reference focal positions of the preset positions 72 to 74 that are the shooting positions during the autofocus operation.

[0030] During operation of the photography tampering detection device 100, the sharpness of the image captured by the camera unit 20 is calculated in order to detect photography tampering of 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 constantly during operation of the photography tampering detection device 100, or may be calculated each time the position for photographing by the camera unit 20 is changed. The autofocus processing unit 312 that performs contrast autofocus processing can use the sharpness of the image captured calculated for the autofocus operation to detect photography tampering of the camera unit 20. In this case, there is no need to perform new image processing for tampering detection, and not only can the processing procedure be simplified, but also the need to provide a new image processing block can be eliminated. If the autofocus processing unit 312 does not calculate the sharpness, the detection unit 314 may calculate the sharpness of the image captured.

[0031] 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 uniform single value regardless of the shooting position of the camera unit 20, or, for example, an individual 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 in a state in which 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 parameter "Sharpness" is initially set as the reference sharpness, as shown in FIG. 3, for example. The initially set "Sharpness" parameter may 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 of FIG. 3, the shooting information of the preset positions 72 to 74 may include "Sharpness Range." The sharpness of the captured image may shift slightly due to changes in 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.

[0032] When a predetermined change occurs in the calculated sharpness of the captured image of the camera unit 20 with respect to the reference sharpness, the detection unit 314 outputs a first detection signal and instructs the autofocus processing unit 312 to execute an autofocus operation. The first detection signal is a signal indicating that a predetermined change in sharpness with respect to the reference sharpness has occurred in the captured images of the preset positions 72 to 74 captured by the camera unit 20. The predetermined change with respect to the reference sharpness includes a case where the calculated sharpness is lowered by a predetermined amount or more from the reference sharpness and a case where the calculated sharpness is changed beyond the allowable range of the reference sharpness. These cases may include a case where the sharpness of the captured image of the preset position is changed by a predetermined amount or more from the predetermined reference sharpness of the preset position. For example, when the focus of the lens block 21 is shifted by a certain distance or more from the in-focus position, the calculated sharpness is lowered by a predetermined amount or more from the reference sharpness. A change in sharpness that exceeds the allowable range of the reference sharpness includes not only 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 focus of the lens block 21 approaches the in-focus position, so it is not generally a problem. However, an extreme increase in sharpness that exceeds the upper limit of the allowable range may occur due to factors other than the focus of the lens block 21 approaching the in-focus position. The detection unit 314 can detect a case where the sharpness becomes extremely high for some reason as a predetermined change relative to the reference sharpness.

[0033] The reference sharpness may be, for example, a uniform single value regardless of the shooting position of the camera unit 20. When the shooting positions of the camera unit 20 are preset positions 72 to 74, the reference sharpness may be defined for each of the preset positions 72 to 74. When the reference sharpness is defined 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 with respect to the reference sharpness of the preset positions 72 to 74 corresponding to the shooting position.

[0034] After the autofocus processing unit 312 executes the 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 that are set as the shooting position. 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 by 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, when the shooting position at the time of outputting the first detection signal and the second detection signal is the preset position 72, the first detection signal and the second detection signal output by the detection unit 314 are detection signals related to the preset position 72.

[0035] The detection unit 314 may be configured to output the second detection signal only when the focus position determination unit 313 determines that the focus of the lens block 21 after the autofocus operation has deviated to the near side closer to the camera unit 20 than the reference focus position. The focal length of the lens block 21 that has defocused to the near side from the reference focus position after the autofocus operation at the preset positions 72 to 74 is shorter than the lower limit of the "Focus Range" of the preset positions 72 to 74. The detection unit 314 regards this state as a state in which an obstruction that interferes with the shooting of the gates 62 to 64 has appeared between the gates 62 to 64 that are originally shot during shooting at the preset positions 72 to 74 and the camera unit 20. The position deviated to the near side from the reference focus position may be determined, for example, by whether or not the focus is closer to the camera unit 20 than the adjustable range of the focus corresponding to the registered "Zoom" parameter of the preset positions 72 to 74 that are the shooting positions. If the focal point of lens block 21 is within the adjustable range, then the focal point can be considered to be substantially located at a position within the "Focus Range" of preset positions 72 to 74 that are set as shooting positions.

[0036] The detection unit 314 may be configured to output a different detection signal 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 ends abnormally.

[0037] The detection state of reduced sharpness for which the detection unit 314 outputs a first detection signal, and the detection state of an abnormality in autofocus operation for 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.

[0038] Next, an example of a processing procedure executed by the photography interference detection device 100 to detect a state in which photography by the camera unit 20 is interfered with in the surveillance camera device 10 of this embodiment will be described with reference to FIG. 4. The photography interference detection device 100 repeatedly executes the processing procedure exemplified 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 with respect 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.

[0039] If the calculated sharpness does not change in a predetermined manner from the reference sharpness (NO in step S102), the process proceeds to step S105 described below. If the calculated sharpness changes in a predetermined manner from the reference sharpness (YES in step S102), the detection unit 314 outputs a first detection signal indicating detection of the predetermined change from 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 that shooting interference has been detected based on the sharpness. After the notification unit 315 outputs the notification signal, the process proceeds to step S105.

[0040] In step S105, the detection unit 314 instructs the autofocus processing unit 312 to execute the autofocus operation of the camera unit 20. The detection unit 314 checks whether the autofocus operation executed by the autofocus processing unit 312 has been completed normally (step S106). If the autofocus operation has not been completed normally but has been abnormally terminated (NO in step S106), the process proceeds to step S108 described later. If the autofocus operation has been completed normally (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 after the autofocus operation has shifted to the near side (step S107). The detection unit 314 checks whether the focus of the lens block 21 after the autofocus operation has shifted to the near side based on the reference focus positions of the preset positions 72 to 74 corresponding to the shooting positions of the camera unit 20.

[0041] The detection unit 314 may confirm that the focus has shifted from the reference focus position to the near side, 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 in the shooting position preset positions 72 to 74. The detection unit 314 may confirm that the focus has shifted from the reference focus position to the near side, when the focal length of the lens block 21 is shorter than the lower limit value of the focus adjustable range corresponding to the "Zoom" parameter registered in the shooting position preset positions 72 to 74.

[0042] If the focus of the lens block 21 after the autofocus operation has not shifted from the reference focus position to the near side (NO in step S107), the series of procedures ends. If the focus after the autofocus operation has shifted from the reference focus position to the near side (YES in step S107), the process proceeds to step S108.

[0043] 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 be, for example, a notification that interference with photography has been detected based on the focal position of the lens block 21 after the autofocus operation of the camera unit 20 and whether or not the autofocus operation has ended abnormally. After the notification unit 315 outputs the notification signal, the series of procedures ends.

[0044] Fig. 5 shows an example of the relationship between possible patterns of photography interference in the surveillance camera device 10 and events occurring in each pattern. In the surveillance camera device 10, scenes in which photography at preset positions 72 to 74 is interfered with include, for example, scenes shown in the leftmost column of Fig. 5.

[0045] Here, with regard to the image sharpness of the image signal captured by the camera unit 20, in each of the scenes of "obstruction," "half of the lens is painted with spray paint," and "strong light hits half of the lens," changes in image sharpness are assumed. The assumed changes in sharpness are, for example, as shown in the second row from the left in FIG. 5, where the image sharpness decreases from the reference sharpness. In each of the scenes of "covered with cloth," "completely painted with spray paint," and "strong light hits the entire lens," it is assumed that the image sharpness significantly decreases from the reference sharpness. In the scene of "changing the camera orientation," depending on the difference in the situation before and after the orientation change, it is assumed that the image sharpness decreases from the reference sharpness, increases from the reference sharpness, or remains unchanged at the reference sharpness by chance.

[0046] An "obstruction" refers to an object that exists between the reference focal positions 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. FIG. 6 shows a state in which a part of the gate 64 is blocked from the field of view of the lens block 21 by a vehicle 80 in the logistics warehouse 60 when the shooting position is preset position 74. In this case, the vehicle 80 corresponds to an "obstruction" that prevents the camera unit 20 from shooting the gate 64.

[0047] When the photographing of the photographing target such as the gates 62-64 of the preset positions 72-74 is obstructed, in most scenes, as shown in FIG. 5, a decrease in the sharpness of the image of the image signal photographed by the camera unit 20 is expected. In this embodiment, the sharpness of the photographed image of the camera unit 20 is calculated during the operation of the photographing interference 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 the photographing interference. The photographing interference detection device 100 can recognize the occurrence of a change in sharpness that may lead to the occurrence of the photographing interference, not just a simple contrast change of the photographed image of the camera unit 20, in a control manner, by the first detection signal. The photographing interference detection device 100 can notify the user of the occurrence of the photographing interference detected based on the sharpness by the notification signal output based on the first detection signal.

[0048] If a value lowered by a predetermined amount from the reference sharpness is set to, for example, the boundary value between the cases where the sharpness is "significantly decreased" 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 decreased by comparing with the calculated sharpness. If a value lowered by a predetermined amount from 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 decreased or significantly decreased by comparing with the calculated sharpness.

[0049] When a predetermined change in the sharpness of the captured image with respect to the reference sharpness, for example, a decrease of a predetermined amount or more with respect 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 caused by the occurrence of shooting interference is not 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 erroneously detected as a scene of shooting interference. 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 the preset positions 72 to 74 by the camera unit 20.

[0050] In this embodiment, when the calculated sharpness falls below the reference sharpness by a predetermined amount or more, and the detection unit 314 and the notification unit 315 output a detection signal and a notification signal of shooting interference, respectively, 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 focal position corresponding to the preset positions 72 to 74 at the start of the autofocus operation.

[0051] Regarding the focus of lens block 21 after autofocus operation, in an "obstruction" scene, as shown in the rightmost column of FIG. 5, the focus of lens block 21 is on the near side of the reference focus position. The near side means the side closer to camera unit 20 than the reference focus position. In a "moving the subject farther away" scene, the focus of lens block 21 after autofocus operation is on the far side of the reference focus position. The far side means the side opposite to the camera unit 20 side of the reference focus position.

[0052] In each of the scenes of "half of the lens is sprayed" and "strong light hits half of the lens", the focus of the lens block 21 after the autofocus operation is nearer or farther than the reference focus position in the preset positions 72 to 74. In the scene of "the camera direction changes", the focus of the lens block 21 after the autofocus operation is nearer or farther than the reference focus position in the preset positions 72 to 74. Alternatively, the autofocus operation may end abnormally because a focusable subject cannot be identified, and the focus of the lens block 21 after the autofocus operation may become unpredictable. In each of the scenes of "covered with cloth", "completely painted with spray", and "strong light hits the entire lens", the autofocus operation may end abnormally and the focus of the lens block 21 after the autofocus operation may become unpredictable.

[0053] In the autofocus operation, when the focal point of the lens block 21 moves toward the camera unit 20 side 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 seen from the camera unit 20. In this case, it is assumed that an "obstructing object" is present in a position on the camera unit 20 side from the preset positions 72 to 74. In the autofocus operation, if the autofocus operation does not end normally, it is presumed that the camera unit 20 is unable to capture a subject that can be focused on. In these states, 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.

[0054] In the 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 interference detection device 100 to recognize the occurrence of an abnormality in the autofocus operation that may lead to the occurrence of photography interference. The abnormality in the autofocus operation includes a shift in 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 interference detection device 100 can notify the user of the occurrence of photography interference detected based on the focus of the lens block 21 by the notification signal output based on the second detection signal. In the photography interference detection device 100 of the first embodiment, if an abnormality in the autofocus operation is detected after the output of a notification signal based on the first detection signal indicating a decrease in the sharpness of the photographed 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.

[0055] [First Modification of the First Embodiment] In the photography interference detection device 100 of the first embodiment, the detection unit 314 checks in step S107 whether the focus of the lens block 21 after the autofocus operation has shifted from the reference focus position to the near side. In the photography interference detection device 100 of the first modification, the detection unit 314 checks in step S107 whether the focus of the lens block 21 after the autofocus operation has shifted from the reference focus position regardless of the near side or the far side. When checking the presence or absence of focus shift regardless of the 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 the autofocus operation has shifted from the reference focus position to the far side, the occurrence of an abnormality in the autofocus operation that may lead to photography interference can be recognized in terms of control by the second detection signal.

[0056] [Second Modification of the First Embodiment] In the photography interference 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 interference based on the sharpness. In this autofocus operation, if the focus of the lens block 21 deviates from the reference focus position or the autofocus operation ends abnormally, a second detection signal indicating abnormal detection of 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 in FIG. 4) after the output of the first detection signal (step S103 in FIG. 4) may be omitted. In the modification of the first embodiment in which the output of the notification signal based on the first detection signal is omitted, when a predetermined change occurs in the sharpness (YES in step S102 in FIG. 4), the detection unit 314 outputs the first detection signal (step S103 in FIG. 4). After outputting the first detection signal, the detection unit 314 instructs the execution of the autofocus operation (step S105 in FIG. 4). The detection unit 314 and the notification unit 315 execute the procedures (steps S106 to S109 in FIG. 4) following confirmation of 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 the modified example, only a notification signal based on the second detection signal is output. In this modified example, when both a change in sharpness that may 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, a notification signal is output. This makes it possible to increase the reliability of the notification of a photography interference state by outputting a notification signal.

[0057] [Second embodiment] In the second embodiment, as shown in the flowchart of FIG. 7, the steps from step S105 in FIG. 4 onward performed in the first embodiment of the photography tampering detection device 100 are all omitted. In the second embodiment, after the first detection signal and the notification signal of the photography tampering based on the sharpness are output (steps S103 and S104), a series of procedures are terminated. In the second embodiment, when a predetermined change occurs in the sharpness with respect to the reference sharpness, the photography tampering detection device 100 detects the change in sharpness that may lead to the occurrence of photography tampering, and can accurately detect photography tampering. In the second embodiment, when the autofocus processing unit 312 performs contrast autofocus processing, the sharpness of the photographed image calculated by the autofocus processing unit 312 for the autofocus operation can be reused. The reused sharpness of the photographed image can be used to detect photography tampering of the camera unit 20. In this case, in the photography tampering detection device 100 of the second embodiment, there is no need to perform new image processing for tampering detection, which not only simplifies the processing procedure but also eliminates the need to provide a new image processing block.

[0058] [Third embodiment] In the photographing interference detection device 100 of the third embodiment, as shown in the flowchart of FIG. 8, when the photographing position of the camera unit 20 is switched to one of the preset positions 72 to 74 (step S201), the process starts. In the started process, the detection unit 314 instructs the autofocus processing unit 312 to execute the 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 has been normally completed (step S203). If the autofocus operation has not been normally completed but has been abnormally completed (NO in step S203), the process proceeds to step S205 described later. If the autofocus operation has been normally completed (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 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 or not the focus of the lens block 21 after the autofocus operation at the preset positions 72 to 74 serving as the shooting positions has deviated from the reference focus position.

[0059] If the focus of lens block 21 after 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 of lens block 21 after autofocus operation has deviated from the reference focus position (YES in step S204), the process proceeds to step S205. In step S205, detection unit 314 outputs a second detection signal. Based on the second detection signal output by detection unit 314, notification unit 315 outputs a notification signal notifying that, for example, shooting interference has been detected based on the focus of lens block 21 (step S206). After notification unit 315 outputs the notification signal, the series of procedures ends.

[0060] After step S207, the procedure of steps S207 to S210 is executed. The process of each step performed in the procedure of steps S207 to S210 is the same as the process performed in steps S101 to S104 of FIG. 7 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 or not the calculated sharpness has a predetermined change from the reference sharpness. If the calculated sharpness has not a predetermined change from the reference sharpness (NO in step S208), the series of procedures ends. If the calculated sharpness has a predetermined change from 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 be, for example, a notification that a shooting hindrance has been detected based on the sharpness. After the notification unit 315 outputs the notification signal, the series of procedures ends.

[0061] The sharpness of the image captured by the camera unit 20 varies depending on whether the camera unit 20 is in focus or not. When the shooting position of the camera unit 20 is switched to one of the preset positions 72 to 74, it is necessary to compare the sharpness of the captured image at the switched shooting position with the reference sharpness. In the shooting interference detection device 100 of the third embodiment, when the shooting position of the camera unit 20 is switched to one of the preset positions 72 to 74, an autofocus operation is performed. Based on the focus of the lens block 21 after this autofocus operation, the occurrence of an abnormality in the autofocus operation that may lead to shooting interference can be recognized more accurately in terms of control. Note that after the processing of the procedure of FIG. 8 is performed, for example, processing according to any of the procedures of the first embodiment, its modified example, and the second embodiment described with reference to FIGS. 4 and 7 may be performed until the shooting position of the camera unit 20 is next switched.

[0062] In the above-described embodiments and modifications other than the second embodiment, when 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 "shooting interference due to an obstruction". Or, when the autofocus operation does not end normally, the user is notified of the occurrence of "shooting interference due to not capturing the subject to be photographed". However, when the focus of the lens block 21 deviates from the reference focus position, including when 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 shooting interference has occurred. Also, different notifications may be made in each of the cases of when the focus of the lens block 21 deviates from the reference focus position to the near side, when the focus deviates from the reference focus position to the far side, and when the autofocus operation ends abnormally.

[0063] In the above embodiment and modified examples, the photography interference detection device 100 is provided in the controller 30, but the photography interference detection device of the present invention may be provided in a part other than the controller 30, such as a computer that communicates with the controller 30 via a network.

[0064] 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 are mutually inconsistent. [Explanation of symbols]

[0065] 20 Camera unit (camera) 21 Lens block 72~74 Preset positions 100 Filming tampering detection device 310 Microcontroller 314 Detection unit 315 Information Department

Claims

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

2. The photography interference 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 focus after the autofocus operation of the camera, which is executed when the sharpness of the image captured by the camera at the preset position has changed from the reference sharpness by more than the predetermined amount, 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 autofocus operation of the camera, which is executed when the sharpness of the image captured by the camera at the preset position has changed from the reference sharpness by more than the predetermined amount, is not completed within a predetermined time from the start of the autofocus operation and terminates abnormally.

4. 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 focus of the camera deviates from the reference focus position of the preset position after the autofocus operation performed when the focus of the camera is not deviated from the reference focus position of the preset position after the autofocus operation, and outputs the first detection signal when the sharpness of the captured image changes by more than the predetermined amount from the reference sharpness of the preset position in a comparison of the sharpness of the captured image with the reference sharpness of the preset position, which is performed when the focus of the camera has not deviated from the reference focus position of the preset position after the autofocus operation.

Images