KR102592230B1 - method for detecting filter switching error of surveillance camera - Google Patents

Abstract

The method for detecting a filter switching abnormality in a surveillance camera according to an embodiment of the present invention includes a first filter corresponding to a day mode and a second filter corresponding to a night mode, the method comprising: A first step of comparing the image data values calculated by passing through the first filter and the second filter, respectively, and comparing the result of the comparison operation with preset reference data to determine whether a hardware defect occurred while the filter was switched. It includes a second step of determining whether or not a filter switching error is detected, and a third step of starting filter reswitching or performing a user notification if it is determined that a filter switching abnormality is detected.

Description

Method for detecting filter switching error of surveillance camera {method for detecting filter switching error of surveillance camera}

An embodiment of the present invention relates to a surveillance camera, and more specifically, to a method for detecting a filter switching abnormality in a surveillance camera equipped with a day/night mode switching function.

Surveillance cameras use the Day & Night function to maintain optimal subject identification during day and night surveillance operations. The Day & Night function generates clear color images by placing an IR-Cut filter that blocks waves in the IR band in front of the image sensor in an environment with sufficient lighting during the day, and by placing a glass filter in front of the image sensor in a low-light environment at night. This is a function that increases the identification of the subject by receiving images of all wavelengths as input and then generating a black-and-white image.

The filter movement method, which is the core of the Day & Night function, uses a motor to move the fixture equipped with the IR-Cut filter and Glass filter. When moving the filter, the filter movement may not operate normally due to a hardware defect or other extreme environmental conditions, resulting in only the color being converted and the filter not being switched. In this case, normal Day & Night functions may not be performed. do.

An embodiment of the present invention detects that an error occurs in hardware filter switching when switching the day/night mode filter of a surveillance camera, thereby overcoming the problem of not performing normal operation because only the color is converted and the filter is not switched. Provides a method for detecting camera filter switching abnormalities.

In order to achieve the above object, the method for detecting a filter switching abnormality of a surveillance camera according to an embodiment of the present invention includes a first filter corresponding to the day mode and a second filter corresponding to the night mode. A method comprising: a first step of comparing image data values calculated by passing through each of the first filter and the second filter; and comparing the result of the comparison operation with preset reference data while the filter is switched. It includes a second step of determining whether a hardware defect has occurred, and a third step of performing filter reswitching or performing a user notification when it is determined that a filter switching abnormality has been detected.

At this time, the first filter may be implemented as an IR-Cut filter and the second filter may be implemented as a dummy glass, and in the first step, the filter may be implemented as hardware from the day mode to the night mode or from the night mode to the day mode. When converted to red, whether the ratio of the Y value of the digital image data when captured using the dummy glass and the Y value of the digital image data when captured using the IR-Cut filter is greater than the first reference value. Step 1-1 of judging; 1-2 for determining whether the difference between the Cr value of the digital image data when captured using the dummy glass and the Cr value of the digital image data when captured using the IR-Cut filter is greater than the second reference value. May include steps.

In addition, the second step determines that a normal filter switching operation has been performed when all of the conditions of the first step and the 1-2 step are satisfied. Otherwise, it is determined that an error has occurred in the filter switching operation. You can judge.

The first reference value may be 1.05, and the second reference value may be 5.

In order to determine whether only a part of the filter is located on the lens due to a hardware defect when the filter is switched, the digital image data of the last row in the moving direction of the switched filter is used to determine the steps 1-1 and Steps 1-2 can be performed.

If the moving direction of the switching filter is from left to right, perform steps 1-1 and 1-2 to determine the Y value and Cr value of the patch in the 2 right columns including the last column in the moving direction. , or when the moving direction of the switching filter is from right to left, the Y value and Cr value in the patch in the 2 left columns including the last column in the moving direction are performed in steps 1-1 and 1-2. It can be done.

According to this embodiment of the present invention, by detecting that an error occurs in hardware filter switching when switching the day/night mode filter of a surveillance camera, the problem of not performing normal operation because only the color is converted and the filter is not switched is overcome. can do.

1 is a block diagram schematically showing the configuration of a surveillance camera equipped with a day/night mode switching function according to an embodiment of the present invention.
FIGS. 2A and 2B are diagrams illustrating the operation of the filter switching unit of the surveillance camera shown in FIG. 1.
Figure 3 is a flowchart illustrating a method for detecting a filter change abnormality in a surveillance camera according to an embodiment of the present invention.

The content described in the background technology column of the above invention is only intended to help understand the background technology of the technical idea of the present invention, and therefore, it can be understood as content corresponding to prior art known to those skilled in the art of the present invention. does not exist.

In the description below, for purposes of explanation and to facilitate understanding of various embodiments, numerous specific details are set forth. However, it is clear that various embodiments may be practiced without these specific details or in one or more equivalent ways. In other instances, well-known structures and devices are shown in block diagrams to avoid unnecessarily obscuring the various embodiments.

Each block in the attached block diagram may be executed by computer program instructions (execution engine), and these computer program instructions may be mounted on a processor of a general-purpose computer, special-purpose computer, or other programmable data processing equipment, so that the computer or The instructions executed through the processor of other programmable data processing equipment create a means of performing the functions described in each block of the block diagram.

These computer program instructions may also be stored in computer-usable or computer-readable memory that can be directed to a computer or other programmable data processing equipment to implement a function in a particular manner, so that the computer-usable or computer-readable memory The instructions stored in can also produce manufactured items containing instruction means that perform the functions described in each block of the block diagram.

In addition, computer program instructions can also be mounted on a computer or other programmable data processing equipment, so a series of operation steps are performed on the computer or other programmable data processing equipment to create a process that is executed by the computer and runs on the computer or other program. Instructions that perform possible data processing equipment may also provide functions for executing functions described in each block of the block diagram.

Additionally, each block may represent a module, segment, or portion of code containing one or more executable instructions for executing specified logical functions, and in some alternative embodiments, the functions mentioned in the blocks or steps may be sequenced. It is also possible to occur outside of .

In other words, it is possible for the two blocks shown to be performed substantially at the same time, and it is also possible for the blocks to be performed in the reverse order of the corresponding functions as needed.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. Throughout the specification, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary. Unless otherwise defined, the terms used herein have the same meaning as commonly understood by a person of ordinary skill in the field to which the present invention pertains.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the attached drawings.

Figure 1 is a block diagram schematically showing the configuration of a surveillance camera equipped with a day/night mode switching function according to an embodiment of the present invention. FIGS. 2A and 2B are diagrams explaining the operation of the filter switching unit of the surveillance camera shown in FIG. 1.

Referring to FIG. 1, the surveillance camera 100 includes a digital signal processor 110, a day/night determination unit 120, a lighting unit 130, a filter unit 140, a filter switching unit 150, a zoom lens 160, It includes a zoom lens driver 170, a focus lens 180, a focus lens driver 190, an imaging device 200, an imaging device controller 210, and an image signal processor 220.

The digital signal processing unit 110 controls the entire operation of the surveillance camera 100, and in particular outputs a control signal to turn on/flash the lighting unit 130 according to the day/night determination result of the day/night determination unit 120, and the filter unit ( 140) controls the operation. Additionally, the digital signal processing unit 110 controls the operations of the zoom lens driving unit 170, the focus lens driving unit 180, and the imaging device control unit 210, and controls the image signal processing operation of the image signal processing unit 220.

The day/night determination unit 120 detects the change between day and night by sensing the illuminance, generates a day/night signal according to the detection result, and outputs it to the digital signal processor 110. The day/night determination unit 120 determines that it is daytime (day mode) when the illuminance sensing result is greater than or equal to a predetermined reference value (e.g., 4LuX), and determines that it is night (night mode) when the illuminance sensing result is less than or equal to the standard value.

Meanwhile, it is desirable to install a light sensor (CdS sensor, not shown) in the surveillance camera 100 to detect the illuminance of light and determine day or night. The optical sensor contains cadmium sulfide (CdS) as its main ingredient, and is preferably formed as a CdS photoconductive cell, which has the characteristic of changing internal resistance depending on incident light energy. In CdS photoconductive cells, the greater the energy of the incident light, the lower the resistance value. In other words, when there is no light energy, it becomes almost like an insulator, and when it receives incident energy, the internal resistance decreases in response to the incident energy, allowing current to flow. In addition, the day/night determination unit 120 may be equipped with a separate illuminance sensor (not shown) to determine day or night based on the results detected by the illuminance sensor.

The lighting unit 130 operates by a lighting control signal or a blinking control signal from the digital signal processing unit 110, and may be composed of an element such as a light emitting diode (LED). When the day/night determination unit 120 determines that it is daytime (day mode), the digital signal processor 110 outputs a blinking control signal to the lighting unit 130, causing the lighting unit 130 to blink and determines that it is night (night mode). When this happens, the digital signal processor 110 outputs a lighting control signal to the lighting unit 130, so that the lighting unit 130 can be turned on.

The filter unit 140 may include a first filter 141, a second filter 142, and a motor 143. The filter unit 140, under the control of the digital signal processor 110, is the first filter in the daytime mode according to the detection result of the day/night determination unit 130, and is an IR-Cut filter that blocks wavelengths in the IR band. (141) is placed in front of the lens to generate a clear color image, and in night mode, that is, in a low-light environment, a dummy glass 142 is placed in front of the lens as the second filter to receive images of all wavelengths, and then a black-and-white image is produced. can be created.

Referring to FIGS. 2A and 2B, the filter switching unit 150 operates the motor 143 to control the digital signal processing unit 110 and operates the motor 143 when the day mode is in the day mode according to the detection result of the day/night determination unit 130. -The cut filter 141 is driven to be positioned in front of the lens, and in the case of night mode, the motor 143 is operated to position the dummy glass 142 in front of the lens.

1 and 2 illustrate a structure in which the second filter (i.e., dummy glass) 142 is positioned in front of the lens in the low-light environment, but the embodiment of the present invention is not limited thereto. As an example, without the dummy glass 142, the first filter (i.e., IR-Cut filter) 141 may be implemented in a form that is covered and peeled off the lens. That is, the structure uses only the lens without using the dummy glass 142 in the night mode. In the day mode, the IR-Cut filter 141 is positioned in front of the lens by operating the motor 143, but in the night mode, the dummy glass 142 is used. Instead of using 142, it is possible to remove only the IR-Cut filter 141 located in front of the lens so that it does not block wavelengths in the IR band. In this case, the second filter 142 may be air rather than dummy glass.

In this way, the optical signal filtered through the day mode and/or the night mode passes through the zoom lens 160 and the focus lens 180 and then reaches the light-receiving surface of the imaging device 200 to form an image of the subject. The image formed on the light-receiving surface of the imaging device 200 is converted into an electrical image signal through photoelectric conversion processing.

The imaging device 200 may be a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor Image Sensor) that converts optical signals into electrical signals. The imaging device 200 as a CMOS has a great advantage in maintaining the power of the surveillance camera 100 due to the low power consumption required for shooting. The manufacturing cost is relatively low, so it is advantageous to increase the area of the imaging device, and it is easy to mass produce. do. The imaging device 200 as a CCD has the advantage of generating much less noise and transmitting image information very quickly compared to CMOS, resulting in fast storage during continuous shooting and excellent image quality.

The positions of the zoom lens 160 and the focus lens 180 are controlled by the zoom lens driver 170 and the focus lens driver 180, respectively. For example, when a wide angle-zoom (zoom-out) signal is generated, the focal length of the zoom lens 160 is shortened to widen the angle of view, and the telephoto (telephoto)-zoom (zoom-in) signal is generated. When a signal is generated, the focus distance of the zoom lens 160 becomes longer and the angle of view becomes narrower.

Since the position of the focus lens 180 is adjusted while the position of the zoom lens 160 is set, the angle of view is hardly affected by the position of the focus lens 180. These zoom lens driver 170, focus lens driver 190, and imaging device control unit 210 control the corresponding components according to results calculated by the digital signal processor 110 based on exposure information, focus information, etc. Thereafter, the image signal output from the imaging device 200 is output to the image signal processing unit 220, and if the image signal input from the imaging device 200 is an analog signal, it is converted into a digital signal, which is processed by the digital signal processing unit. Various image processing is performed on the converted digital video signal through 110. The video signal that has undergone this processing may be temporarily stored inside the surveillance camera 100 and then transmitted to a digital video recorder or network video recorder. Specifically, the image signal processing unit 220 improves image quality by performing signal processing such as Auto White Balance, Auto Exposure, and Gamma Correction to convert image data to suit human vision. It is possible to improve and output video signals with improved image quality. Additionally, the digital signal processor 110 may perform image processing such as color filter array interpolation, color matrix, color correction, and color enhancement.

A method for detecting filter switching abnormalities in a surveillance camera according to an embodiment of the present invention may be performed inside a surveillance camera driving device as shown in FIG. 2. Depending on the embodiment, the main algorithm of the operation method is based on the detection of peripheral components within the device. With help, it can be performed within the control unit, that is, the digital signal processing unit 110.

When in day mode according to the detection result of the day/night determination unit 130 under the control of the digital signal processor 110, the filter switching unit 150 operates the motor 143 to place the IR-Cut filter 141 in front of the lens. In the case of night mode, the motor 143 is operated to position the dummy glass 142 in front of the lens.

In day mode, the IR-Cut filter 141 is a filter that can only pass through the visible ray range that can be recognized by humans, and cuts off the IR ray range so that it enters the lens. On the other hand, in the case of night mode, all wavelength bands are passed through and switched to dummy glass 142 to better respond to noise or low-light situations. The dummy glass 142 passes all wavelength bands, resulting in a difference in the amount or wavelength of light condensing on the lens compared to the IR-Cut filter 141.

However, there may be cases where the filter is not switched to the dummy glass 142 and IR-Cut filter 141 due to hardware defects or various other reasons. In other words, the IR-Cut filter 141 may not be controlled to be positioned in the day mode, and the dummy glass 142 may not be controlled to be positioned in the night mode. In this case, if the above error is not detected, it may malfunction. Video is captured.

In order to overcome these problems, the purpose of the embodiment of the present invention is to provide a method for detecting filter switching abnormalities in surveillance cameras that can detect through software that an error occurs in hardware filter switching when switching day/night mode filters of a surveillance camera. .

When the filter switching from day mode to night mode is performed, as mentioned above, the filter switching unit 150 drives the motor 143 of the filter unit 140 to turn the IR-Cut filter 141 located in front of the lens into a dummy. Converted to glass (142). Referring to FIG. 2B, in the embodiment of the present invention, when the filter is switched from the day mode to the night mode, the filter unit 140 may move from right to left.

Likewise, when a filter switch is performed from the night mode to the day mode, the filter switching unit 150 drives the motor 143 of the filter unit 140 to change the dummy glass 142 located in front of the lens to the IR-Cut filter 141. ) is converted to Referring to FIG. 2A, in the embodiment of the present invention, when the filter is switched from the night mode to the day mode, the filter unit 140 may move from left to right.

In this way, when the filter is hardware switched from day mode to night mode, or from night mode to day mode, the present invention is implemented as a method of detecting whether an error occurred in the filter switch, that is, whether the filter was switched properly. For example, by comparing and analyzing predetermined conditions, abnormal detection of filter switching of a surveillance camera can be identified through software.

Figure 3 is a flowchart explaining a method for detecting a filter switching abnormality in a surveillance camera according to an embodiment of the present invention. Hereinafter, a specific method for detecting a filter switching abnormality in a surveillance camera will be described with reference to Figures 1 to 3.

The filter unit 140 of the surveillance camera 100 is under the control of the digital signal processing unit 110, and in the case of day mode according to the detection result of the day/night determination unit 130, a first filter (IR) blocks wavelengths in the IR band. -Cut filter) (141) is placed in front of the lens to create a clear color image, and in night mode, that is, in a low-light environment, a second filter (dummy glass or air) (142) is placed in front of the lens to produce images in all wavelength ranges. After receiving input, you can create a black and white image.

An embodiment of the present invention is a predetermined method that can detect anomalies in filter switching of the surveillance camera 100 in software when the filter is hardware switched from day mode to night mode, or from night mode to day mode. As the conditions, the first condition for comparing the digital image data information sensed through the IR-Cut filter 141 and the digital image data information sensed through the dummy glass 142 under the same light source and the filter is switched. The second condition is used to determine whether only part of the filter is located on the lens due to a hardware defect. If both the first and second conditions are satisfied, the filter of the surveillance camera is properly operated. It is determined that it has been switched, and if not, it is determined that a filter switching error has been detected and the motor can be started to re-switch the filter or a notification can be sent to the user.

In other words, the method of detecting a filter switching abnormality of a surveillance camera according to an embodiment of the present invention compares and calculates the image data values calculated by passing through the first filter corresponding to the day mode and the second filter corresponding to the night mode, respectively. A step of comparing the result of the comparison operation with preset reference data to determine whether only a part of the filter is located on the lens due to a hardware defect while the filter is being switched, and determining that a filter switching abnormality has been detected. If this happens, it may include a step of performing filter reswitching or user notification.

In more detail, the first condition is described as follows.

The image signal captured through the surveillance camera 100 shown in FIG. 1 is an analog RGB image signal converted into a digital image signal, that is, a luminance signal Y and chrominance signals Cb and Cr signals through the image signal processor 220. It may be converted and provided to the digital signal processor 110.

At this time, under the same light source conditions, the Y value of the digital image signal corresponding to the case where the light passes through the IR-Cut filter 141 and the Y value of the digital image signal corresponding to the case where the light passes through the dummy glass 142 are determined. In comparison, since a certain frequency region (e.g., infrared frequency region) of the light source is removed under the IR-Cut filter 141, the Y value (Y(IR-cut)) when it passes through the dummy glass 142 The expected value becomes smaller than the value (Y(Dummy)). In other words, the condition Y(Dummy) > Y(IR-cut) can be used to detect filter switching abnormalities as the basic first condition (1-1 condition).

The above 1-1 condition can be summarized in a more specific formula (Equation 1) as follows.

(Equation 1)

Y(Dummy) / Y(IR-Cut) > First reference value (A)

The reflectance of the Y value (Y(Dummy)) when passing through the dummy glass 142 and the Y value (Y(IR-Cut)) under the IR-Cut filter 141 differs by at least 5%. Therefore, it is desirable that the first reference value (A) is 1.05.

Therefore, when a filter switching operation is performed, the ratio of the Y value (Y(Dummy)) when passing through the dummy glass 142 and the Y value (Y(IR-Cut)) under the IR-Cut filter 141 is 1 Determine whether it is greater than the reference value (A). That is, it is determined whether the 1-1 condition (Equation 1) is satisfied (ST 110).

At this time, if the 1-1 condition (Equation 1) is satisfied, it is determined whether the condition of the next step is satisfied; otherwise, it is determined that an error has occurred in the filter switching operation (ST 140).

Additionally, in the case of the Cr value, which is a color difference signal, in addition to the Y value, which is the luminance signal of a digital image signal, the wavelength region of light that was removed when switching from the IR-Cut filter 141 to the dummy glass 142 is passed through, so the IR- The Cr value (CR(IR-Cut)) under the cut filter 141 becomes smaller than the Cr value (CR(Dummy)) when passing through the dummy glass 142. In other words, the CR(Dummy) > CR(IR-Cut) condition can be used as an additional first condition (1st-2nd condition) to detect a filter switching abnormality.

However, in the case of the Cb value, the directionality varies depending on the color temperature, so in the embodiment of the present invention, the Cr value with a directionality that increases regardless of the color temperature of the light source is used.

The above conditions 1-2 can be summarized in a more specific equation (Equation 2) as follows.

(Equation 2)

CR(Dummy) - CR(IR-Cut) > 2nd reference value (B)

The Cr value is displayed as a negative or positive number depending on the position. The Cr value (CR(Dummy)) when passing through the dummy glass 142 and the Cr value (CR(IR-Cut)) under the IR-Cut filter 141 If added, it must increase by at least the second standard value (B). In the case of the embodiment of the present invention, the second reference value (B) is preferably implemented as at least 5 or more.

Therefore, when a filter switching operation is performed, the difference between the Cr value (CR(Dummy)) when passing through the dummy glass 142 and the Cr value (CR(Dummy)) under the IR-Cut filter 141 is the second reference value. Determine whether it is greater than (B). That is, it is determined whether the first-second condition (Equation 2) is satisfied (ST 130).

At this time, the 1-1 condition (Equation 1) and the 1-2 condition (Equation 2) are applied using the digital image data of the last column in the direction in which the filter unit 140 moves. As a result, if both the 1-1 condition and the 1-2 condition are satisfied, it is determined that a normal filter switching operation has been performed (ST 130). Otherwise, it is determined that an error has occurred in the filter switching operation. (ST 140). Additionally, if it is determined that a filter switching abnormality has been detected, filter reswitching may be initiated or a user notification may be performed.

A basic conditional expression has been prepared to detect a filter switching error using the first condition, that is, the 1-1 condition and the 1-2 condition, but the first condition is a hardware defect during filter switching. If only a portion of is located on the lens, the corresponding abnormality cannot be detected.

As an example, when the IR-Cut filter 141 stops while being converted to the dummy glass 142, the 1-1 condition (Equation 1) and the 1-2 condition (Equation 1) for the entire area of the filter unit 140 ( If Equation 2) is applied, an abnormality may not be detected and it may be mistakenly judged that a normal conversion has been performed. Therefore, the embodiment of the present invention adds a condition for excluding the area detecting the 1-1 condition (Equation 1) and the 1-2 condition (Equation 2) as an additional second condition in addition to the first condition. It can be applied.

In an embodiment of the present invention, the 1-1 condition (Equation 1) and the 1-2 condition (Equation 2) are calculated using the digital image data of the last column in the direction in which the filter unit 140 moves. Detected with

That is, as shown in FIG. 2A, when the moving direction of the filter unit 140 is from left to right, the Y value and Cr value in the two right column patches including the last column in the moving direction are the first - Detected using condition 1 (Equation 1) and condition 1-2 (Equation 2). Likewise, as shown in FIG. 2B, when the moving direction of the filter unit 140 is from right to left, the Y value and Cr value of the patch in the left two columns including the last column in the moving direction are the first - Detected using condition 1 (Equation 1) and condition 1-2 (Equation 2).

As described above, the present invention has been described with specific details such as specific components and limited embodiments and drawings, but this is only provided to facilitate a more general understanding of the present invention, and the present invention is not limited to the above embodiments. , those skilled in the art can make various modifications and variations from this description.

Accordingly, the spirit of the present invention should not be limited to the described embodiments, and the scope of the patent claims described below as well as all modifications that are equivalent or equivalent to the scope of this patent claim shall fall within the scope of the spirit of the present invention. .

Claims (6)

In a method for detecting a filter switching abnormality of a surveillance camera including a first filter corresponding to a day mode and a second filter corresponding to a night mode,
A first step of comparing and calculating a first image data value calculated by passing the first filter and a second image data value calculated by passing the second filter;
A second step of determining whether a hardware defect occurred while the filter was switched by comparing a result of a comparison operation between the first image data value and the second image data value with preset reference data;
A method for detecting a filter switching abnormality in a surveillance camera, comprising a third step of performing filter reswitching or performing a user notification when it is determined that a filter switching abnormality has been detected. ◈Claim 2 was abandoned upon payment of the setup registration fee.◈ According to claim 1,
The first filter is implemented as an IR-Cut filter, and the second filter is implemented as a dummy glass,
The first step is,
When the filter is hardware switched from the day mode to the night mode, or from the night mode to the day mode,
1-1 for determining whether the ratio of the Y value of the digital image data when captured using the dummy glass and the Y value of the digital image data when captured using the IR-Cut filter is greater than the first reference value. step;
1-2 for determining whether the difference between the Cr value of the digital image data when captured using the dummy glass and the Cr value of the digital image data when captured using the IR-Cut filter is greater than the second reference value. A method for detecting filter switching abnormalities in a surveillance camera including the following steps. ◈Claim 3 was abandoned upon payment of the setup registration fee.◈ According to clause 2,
The second step is,
If all the conditions of step 1-1 and step 1-2 are satisfied, it is determined that a normal filter switching operation has been performed. Otherwise, it is determined that an error has occurred in the filter switching operation. Filter switching abnormality of a surveillance camera Detection method. ◈Claim 4 was abandoned upon payment of the setup registration fee.◈ According to clause 2,
A method for detecting a filter change abnormality in a surveillance camera where the first reference value is 1.05 and the second reference value is 5. ◈Claim 5 was abandoned upon payment of the setup registration fee.◈ According to paragraph 2,
In order to determine whether only a part of the filter is located on the lens due to a hardware defect when the filter is switched, the digital image data of the last row in the moving direction of the switched filter is used to determine the steps 1-1 and A method of detecting a filter switching abnormality of a surveillance camera performing steps 1-2. ◈Claim 6 was abandoned upon payment of the setup registration fee.◈ According to clause 5,
If the moving direction of the switching filter is from left to right, perform steps 1-1 and 1-2 to determine the Y value and Cr value of the patch in the 2 right columns including the last column in the moving direction. , or
When the moving direction of the switching filter is from right to left, the Y value and Cr value of the patch in the 2 left columns including the last column in the moving direction are calculated by performing steps 1-1 and 1-2. Method for detecting filter switching abnormalities in surveillance cameras.

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