Abstract:
Disclosed is a surveillance apparatus such as a surveillance camera and a digital video recorder. The surveillance apparatus includes: an analog-to-digital converter configured to convert an analog video signal, of at least one image of a region captured by an optical system, into digital video data of the region; and a main controller configured to detect a current motion region from the digital video data of the region, remove a high frequency component of the region except the current motion region, and transmit the digital video data of the region, from which the high frequency component is removed, to a target device over a communication network.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Korean Patent Application No. 10-2014-0005604, filed on Jan. 16, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Apparatuses and methods consistent with exemplary embodiments relate to a surveillance camera and a digital video recorder, which are used in a surveillance system. 
         [0004]    2. Description of the Related Art 
         [0005]    With the advance of technology of an image sensor of an optical-to-electrical device (for example, a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS)) applied to cameras, the cameras may generate high-resolution live view video data. 
         [0006]    However, regarding a state of a communication network or performances of client terminals, it is not easy to transmit high-resolution live view video data to the client terminals over the communication network. 
         [0007]    Therefore, in the case of a surveillance camera that transmits digital video data to client terminals or a network video recorder over the communication network, the digital video data is compressed at a high compression rate by a surveillance camera so as to reduce the amount of transmitted data. 
         [0008]    Moreover, in the case of a digital video recorder that receives analog video data from surveillance cameras, the analog video data is converted into digital video data by the digital video recorder, the digital video data is compressed at a high compression rate so as to reduce the amount of transmitted and stored data, and the compressed digital video data is transmitted to client terminals over a communication network. 
         [0009]    In surveillance cameras or digital video recorders of the related art, when a bandwidth of the communication network is narrow, digital video data compressed at a high compression rate is transmitted, and thus, unclear videos are displayed at client terminals. For this reason, the surveillance effects of the client terminals are reduced. 
       SUMMARY 
       [0010]    One or more exemplary embodiments provide a surveillance apparatus such as a surveillance camera and a digital video recorder, which transmits video data, which is effective for a user, to a target device despite a large amount of data to be transmitted. 
         [0011]    Various aspects of the exemplary embodiments will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of these embodiments. 
         [0012]    According to an aspect of an exemplary embodiment, there is provided a surveillance apparatus which may include an analog-to-digital converter configured to convert an analog video signal, of at least one image of a region captured by an optical system, into digital video data of the region; and a main controller configured to detect a current motion region from the digital video data of the region, remove a high frequency component of the region except the current motion region, and transmit the digital video data of the region, from which the high frequency component is removed, to a target device over a communication network. 
         [0013]    A high frequency component of an image may be removed by applying low pass filtering on the image. Here, if the main controller does not detect the current motion region from the digital video data of the region, the main controller may perform low pass filtering on the digital video data of the region except the current motion region to remove the high frequency component of the region except the current motion region. 
         [0014]    The main controller may be further configured to detect a predetermined target in the region. If the current motion region is detected from the digital video data of the region, and the predetermined target is detected from the current motion region, the main controller may perform low pass filtering on the digital video data of the region except the current motion region, to remove the high frequency component of the region except the current motion region. 
         [0015]    However, even when the current motion region is detected from the digital video data of the region, if the predetermined target is not detected from the current motion region, the main controller may perform low pass filtering on the digital video data of the region, that is, the entire digital video data, to remove a high frequency component of the digital video data of the region. 
         [0016]    According an aspect of another exemplary embodiment, there is provided a method of processing video data which may include: converting an analog video signal, of at least one image of a region captured by an optical system, into digital video data of the region; detecting a current motion region from the digital video data of the region; removing a high frequency component of the region except the current motion region if the current motion region is detected; and transmitting the digital video data, from which the high frequency component is removed, to a target device over a communication network. 
         [0017]    The method may further include compressing the digital video data of the region. 
         [0018]    Specifically, the method may further include compressing the digital video data on which the low pass filtering is performed without compressing the digital video data on which the low pass filtering is not performed, if the current motion region is detected from the digital video data of the region. 
         [0019]    According to an aspect of still another exemplary embodiment, there is provided a computer recording medium having recorded thereon a program for executing the above method. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which: 
           [0021]      FIG. 1  is a diagram illustrating a surveillance system including surveillance cameras according to an exemplary embodiment; 
           [0022]      FIG. 2  is a diagram illustrating an internal configuration of one of the surveillance cameras of  FIG. 1 , according to an exemplary embodiment; 
           [0023]      FIG. 3  is a flowchart illustrating an operation of a main controller of  FIG. 2 , according to an exemplary embodiment; 
           [0024]      FIG. 4  is a diagram illustrating a video frame from which a motion region is detected, according to an exemplary embodiment; 
           [0025]      FIG. 5  is a diagram illustrating an example of a 3×3 mask of a low pass filter which is to be used for a region except a current motion region, according to an exemplary embodiment; 
           [0026]      FIG. 6  is a flowchart illustrating an operation of the main controller of  FIG. 2 , according to an exemplary embodiment; 
           [0027]      FIG. 7  is a flowchart illustrating an operation of the main controller of  FIG. 2 , according to an exemplary embodiment; 
           [0028]      FIG. 8  is a block diagram illustrating an example of an internal configuration of the main controller of  FIG. 2 , according to an exemplary embodiment; 
           [0029]      FIG. 9  is a diagram illustrating a surveillance system including a digital video recorder according to another exemplary embodiment of the present invention; 
           [0030]      FIG. 10  is a diagram illustrating an internal configuration of the digital video recorder of  FIG. 9 , according to an exemplary embodiment; 
           [0031]      FIG. 11  is a flowchart illustrating an operation of a main controller of  FIG. 10 , according to an exemplary embodiment; 
           [0032]      FIG. 12  is a flowchart illustrating an operation of the main controller of  FIG. 10 , according to an exemplary embodiment; 
           [0033]      FIG. 13  is a flowchart illustrating an operation of the main controller of  FIG. 10 , according to an exemplary embodiment; and 
           [0034]      FIG. 14  is a block diagram illustrating an internal configuration of the main controller of  FIG. 10 , according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    Reference will now be made in detail to exemplary embodiments which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, these embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the inventive concept. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. 
         [0036]    Moreover, the present specification and the drawings are not provided for the purpose of limiting the inventive concept, and the spirit and scope of the inventive concept should be defined by claims. The terms or words used in the present specification and claims should be interpreted based on the meanings and concepts corresponding to technical aspects of the inventive concept. 
         [0037]    Hereinafter, the exemplary embodiments of the inventive concept will be described in detail with reference to the accompanying drawings. In addition, in the present specification and drawings, like reference numerals refer to like elements throughout, and thus, redundant descriptions are omitted. 
         [0038]      FIG. 1  is a diagram illustrating a surveillance system including a plurality of surveillance cameras  101   a  to  101   n  according to an exemplary embodiment. 
         [0039]    In  FIG. 1 , reference numeral D IMA  refers to digital video data which is transmitted from each of the surveillance cameras  101   a  to  101   n  to a communication network  103  (for example, the Internet), or transmitted from the communication network  103  to a plurality of client terminals  104   a  to  104   m.    
         [0040]    Reference numeral D IMAT  refers to digital video data which is transmitted from the communication network  103  to a network video recorder (NVR)  102 , or transmitted from the NVR  102  to the communication network  103 . 
         [0041]    Referring to  FIG. 1 , the NVR  102  is connected to the surveillance cameras  101   a  to  101   n  and the client terminals  104   a  to  104   m  over the communication network  103 , for example, the Internet. 
         [0042]    Each of the surveillance cameras  101   a  to  101   n  obtains the digital video data D IMA , and transmits the obtained digital video data D IMA  to at least one target device over the communication network  103 . 
         [0043]    In the surveillance system of  FIG. 1 , a target device for the surveillance cameras  101   a  to  101   n  according to the present embodiment is the NVR  102 . However, the surveillance cameras  101   a  to  101   n  may directly transmit digital video data to the client terminals  104   a  to  104   m  over the communication network  103 . That is, the target device for the surveillance cameras  101   a  to  101   n  according to the present embodiment may be each of the client terminals  104   a  to  104   m.    
         [0044]    The NVR  102  loads and stores packets (which are received by channel) in a volatile memory, and transmits the packets. That is, the NVR  102  transmits video data, which are loaded by channel in the volatile memory, to the client terminals  104   a  to  104   m,  and stores the video data in a recording medium. 
         [0045]    The surveillance cameras  101   a  to  101   n  according to the present embodiment will be described in detail with reference to  FIGS. 2 to 8 . 
         [0046]      FIG. 2  is a diagram illustrating an internal configuration of the surveillance camera  101   n  of  FIG. 1 . 
         [0047]    An internal configuration and operation of the surveillance camera  101   n  according to the present embodiment will now be described in detail with reference to  FIGS. 1 and 2 . 
         [0048]    The surveillance camera  101   n  according to the present embodiment includes an optical system (OPS), an optical-to-electrical converter (OEC), an analog-to-digital converter (ADC)  201 , a timing circuit  202 , a dynamic random access memory (DRAM)  204 , an electrically erasable and programmable read only memory (EEPROM)  205 , a flash memory (FM)  206 , a main controller  207 , and a communication interface  209 . 
         [0049]    The OPS includes a lens unit and a filter unit, and optically processes light from a subject. 
         [0050]    The OEC of a CCD or a CMOS converts light, transferred from the OPS, into an electrical analog signal. Here, the main controller  207  controls the timing circuit  202  to thereby control operations of the OEC and the ADC  201 . 
         [0051]    The ADC  201  processes an analog video signal from the OEC to remove high frequency noise and adjust an amplitude, and then converts the analog video signal into digital video data D IM1 . The digital video data D IM1  is input to the main controller  207 . 
         [0052]    The timing circuit  202  controls the operations of the OEC and the ADC  201  according to a synchronization signal from the main controller  207 . 
         [0053]    The DRAM  204  temporarily stores digital video data from the main controller  207 . The EEPROM  205  stores a program that is necessary for an operation of the main controller  207 . The flash memory  206  stores preset or predetermined data that is necessary for an operation of the main controller  207 . 
         [0054]    The main controller  207  communicates with the NVR  102  (which is a target device) over the communication interface  209 , and transmits the digital video data D IMA  to the NVR  102 . 
         [0055]    Here, the main controller  207  detects a current motion region from the digital video data D IM1  transferred from the ADC  201 , removes a high frequency component of a region except the detected current motion region, and transmits the digital video data D IMA  (which corresponds to the removal result) to the NVR  102  (which is the target device) through the communication interface  209  and the communication network  103 . In the present embodiment, the main controller  207  performs a low pass filtering operation on video data of the region except the current motion region. 
         [0056]    Therefore, the high frequency component of the region except the current motion region is removed by the low pass filtering operation, and thus, the amount of data is reduced in a region unnecessary for surveillance. Accordingly, despite a large amount of data to be transmitted, video data effective for a user is transmitted to a target device. 
         [0057]    For example, when digital video data obtained by removing a high frequency component of the region except the current motion region is additionally compressed and transmitted, the relatively reduced amount of data is compressed, and thus, even when video data is compressed at a relatively low compression rate, the amount of compressed data may not relatively increase. Also, since a relatively low compression rate is applied, a current motion region necessary for surveillance becomes clearer. 
         [0058]      FIG. 3  illustrates an operation of the main controller  207  of  FIG. 2 , according to an exemplary embodiment.  FIG. 4  illustrates a video frame  40  from which a motion region is detected, according to an exemplary embodiment. In  FIG. 4 , reference numeral  402   a  refers to a motion target.  FIG. 5  is a diagram illustrating an example of a 3×3 mask  501  of a low pass filter which is to be used for a region  401  except a current motion region  402  of  FIG. 4 . 
         [0059]    The first example of the operation of the main controller  207  will now be described with reference to  FIGS. 2 to 5 . 
         [0060]    In operation S 301 , the main controller  207  adjusts an average luminance of the digital video data D IM1  from the ADC  201 . 
         [0061]    In operation S 303 , the main controller  207  removes noise of the digital video data. 
         [0062]    In operation S 305 , the main controller  207  changes a resolution of the digital video data to a preset resolution. 
         [0063]    In operation S 307 , the main controller  207  detects a current motion region from the digital video data. The current motion region may be a region which shows a motion having at least a threshold value. 
         [0064]    If the current motion region  402  is detected in operation S 309 , the main controller  207  performs a low pass filtering operation on video data of the region  401  except the current motion region  402  to remove a high frequency component from this video data, in operation S 311 . 
         [0065]    In the present embodiment, the low pass filtering operation denotes an operation in which pixel values of the video data of the region  401  except the current motion region  402  are multiplied by a filter coefficient that is greater than a decimal number 0 and less than a decimal number 1. For example, the 3×3 mask  501  having a filter coefficient of 1/9 is used, and thus, the pixel values of the video data of the region  401  except the current motion region  402  are reduced by 1/9 times. 
         [0066]    Here, the filter coefficient increases in proportion to the number of previously-occurred motions in the region  401  except the current motion region  402 . For example, when the number of previously-occurred motions in the region  401  except the current motion region  402  is 14, the filter coefficient is 1/9, and when the number of previously-occurred motions in the region  401  except the current motion region  402  is 7, the filter coefficient is 1/18. Therefore, sharpness or resolution may be determined in proportion to an importance of the region  401  except the current motion region  402 . 
         [0067]    When the current motion region  402  is not detected in operation S 309 , the main controller  207  performs the low pass filtering operation on video data of all the regions  401  and  402  to remove the high frequency component therefrom, in operation S 313 . 
         [0068]    Subsequently, the main controller  207  compresses digital video data, and transmits video data, corresponding to the compression result, to the NVR  102  (see  FIG. 1 ) which is a target device, in operation S 315 . However, depending on the case, the digital video data may be transmitted without being compressed. 
         [0069]    Operations S 301  to S 315  are periodically repeated until an end signal is generated in operation S 317 . 
         [0070]      FIG. 6  illustrates an operation of the main controller  207  of  FIG. 2 , according to another exemplary embodiment. This operation of the main controller  207  will now be described with reference to  FIGS. 2 and 4  to  6 . 
         [0071]    In operation S 601 , the main controller  207  adjusts the average luminance of the digital video data D IM1  from the ADC  201 . 
         [0072]    In operation S 603 , the main controller  207  removes noise of the digital video data. 
         [0073]    In operation S 605 , the main controller  207  changes the resolution of the digital video data to the preset resolution. 
         [0074]    In operation S 607 , the main controller  207  detects a current motion region from the digital video data. 
         [0075]    If the current motion region  402  is not detected in operation S 609 , the main controller  207  performs the low pass filtering operation on video data of all the regions  401  and  402  to remove the high frequency component therefrom in operation S 615 . 
         [0076]    If the current motion region  402  is detected in operation S 609 , the main controller  207  determines whether a predetermined target  402   a  is detected from the current motion region  402 , in operation S 611 . 
         [0077]    Here, kinds of the predetermined target  402   a  are various depending on the surveillance purpose of the surveillance system. That is, regarding the advance of motion detection technology including object classification technology, the predetermined target  402   a  may be a person, an animal, or a vehicle which moves in a specific manner, may be a person or an animal which has a specific shape and color, or may be a specific object. 
         [0078]    However, periodically-moving objects (for example, a tree shaken by wind, a rotating electric fan, an ascending/descending elevator, etc.) may be set as a non-moving target. 
         [0079]    If the predetermined target  402   a  is not detected in operation S 611 , the main controller  207  performs the low pass filtering operation on the video data of all the regions  401  and  402  to remove the high frequency component therefrom, in operation S 615 . 
         [0080]    If the predetermined target  402   a  is detected in operation S 611 , the main controller  207  performs the low pass filtering operation on the video data of the region  401  except the current motion region  402  to remove the high frequency component in operation S 613 . 
         [0081]    Subsequently, the main controller  207  compresses digital video data, and transmits video data, corresponding to the compression result, to the NVR  102  (see  FIG. 1 ) which is a target device, in operation S 617 . However, depending on the case, the digital video data may be transmitted without being compressed. 
         [0082]    Operations S 601  to S 617  are periodically repeated until the end signal is generated in operation S 619 . 
         [0083]    According to an exemplary embodiment, the main controller  207  may first determine the predetermined target  402   a  is detected in the region  401 , and then, determine whether the predetermined target  402   a  generates a motion which satisfies a predetermined condition. Depending on a result of these determinations, the main controller  207  may select where in the region  401  the low pass filtering operation is to be performed. 
         [0084]      FIG. 7  illustrates an operation of the main controller  207  of  FIG. 2 , according to still another exemplary embodiment. This operation of the main controller  207  will now be described with reference to  FIGS. 2 ,  4 ,  5  and  7 . 
         [0085]    In operation S 701 , the main controller  207  adjusts the average luminance of the digital video data D IM1  from the ADC  201 . 
         [0086]    In operation S 703 , the main controller  207  removes noise of the digital video data. 
         [0087]    In operation S 705 , the main controller  207  changes the resolution of the digital video data to the preset resolution. 
         [0088]    In operation S 707 , the main controller  207  detects a current motion region from the digital video data. 
         [0089]    If the current motion region  402  is detected in operation S 709 , the main controller  207  performs the low pass filtering operation on the video data of the region  401  except the current motion region  402 , in operation S 711 . Also, the main controller  207  compresses the video data of the region  401  except the current motion region  402 , and transmits video data, corresponding to the compression result, to the NVR  102  (see  FIG. 1 ) which is a target device, in operation S 713 . 
         [0090]    If the current motion region  402  is not detected in operation S 709 , the main controller  207  performs the low pass filtering operation on the video data of all the regions  401  and  402  to remove the high frequency component therefrom, in operation S 715 . Also, the main controller  207  compresses the digital video data of all the regions  401  and  402 , and transmits video data, corresponding to the compression result, to the NVR  102  (see  FIG. 1 ) which is a target device, in operation S 717 . 
         [0091]    Operations S 701  to S 717  are periodically repeated until the end signal is generated in operation S 317 . 
         [0092]      FIG. 8  illustrates an internal configuration of the main controller  207  of  FIG. 2 , according to an exemplary embodiment. The internal configuration of the main controller  207  will now be described in detail with reference to  FIGS. 2 and 8 . 
         [0093]    The main controller  207  includes an auto gain controller (AGC)  801 , a noise remover  802 , a scalier  803 , a motion detector  804 , a low pass filter (LPF)  805 , a compression setter  806 , a compressor  807 , and a core processor  808 . 
         [0094]    The AGC  801  adjusts the average luminance of the digital video data D IM1  from the ADC  201 . 
         [0095]    The noise remover  802  removes noise of the digital video data D IM2  output from the AGC  801 . 
         [0096]    The scalier  803  changes a resolution of digital video data D IM3 , output from the noise remover  802 , to the preset resolution. 
         [0097]    The motion detector  804  detects a current motion region from digital video data D IM4  output from the scalier  803 . 
         [0098]    The LPF  805  filters out the high frequency component of a region except a current motion region in the digital video data D IM4  output from the scalier  803 , according to information about the current motion region received from the motion detector  804 . 
         [0099]    The compression setter  806  generates information about a compression exclusion region  806  according to the information about the current motion region from the motion detector  804 . 
         [0100]    The compressor  807  compresses a region except the compression exclusion region  806  in digital video data D IM5  output from the LPF  805 , according to information about the compression exclusion region  806  from the compression setter  806 , and outputs the digital video data D IMA , corresponding to the compression result, to a communication interface (CI)  209 . 
         [0101]    The core processor  808  controls operations of the AGC  801 , the noise remover  802 , the scalier  803 , the motion detector  804 , the LPF  805 , the compression setter  806 , and the compressor  807 . 
         [0102]      FIG. 9  illustrates a surveillance system including a digital video recorder  902  according to another exemplary embodiment. 
         [0103]    Referring to  FIG. 9 , a plurality of surveillance cameras  901   a  to  901   n  respectively transmit analog video signals S VID1  to S VID(n)  to the digital video recorder  902 . 
         [0104]    The digital video recorder  902  according to the present embodiment converts the analog video signals S VID1  to S VID(n) , respectively output from the surveillance cameras  901   a  to  901   n,  into digital video data, stores digital video data D IMAT  corresponding to the conversion result, and transmits the digital video data D IMAT  to a plurality of target devices  904   a  to  904   m  over a communication network  903 . In the present embodiment, the communication network  903  is the Internet, the target devices  904   a  to  904   m  are client terminals. In  FIG. 9 , reference numeral D IMAT  refers to digital video data which is transmitted from the digital video recorder  902  to the communication network  903 , and reference numeral D IMA  refers to digital video data which is transmitted from the communication network  103  to the client terminals  904   a  to  904   m.    
         [0105]    The digital video recorder  902  according to the present embodiment will be described in detail with reference to  FIGS. 10 to 14 . 
         [0106]      FIG. 10  illustrates an internal configuration of the digital video recorder  902  of  FIG. 9 . An internal configuration and operation of the digital video recorder  902  according to the present embodiment will now be described in detail with reference to  FIGS. 9 and 10 . 
         [0107]    The digital video recorder  902  according to the present embodiment includes an ADC  1001 , a communication interface  1005 , a random access memory (RAM)  1006 , a main controller  1007 , a compressor  1008 , and a recording medium  1009 . Here, depending on the case, the compressor  1008  may not be provided. 
         [0108]    The ADC  1001  converts analog video signals S VID   1  to S VID (n), respectively output from the surveillance cameras  901   a  to  901   n,  into digital video data D IMA   1  to D IMA (n), respectively. 
         [0109]    The main controller  1007  stores data in the RAM  1006 , controls the compressor  1008  to compress the digital video data D IMA   1  to D IMA (n) of respective channels, and stores the digital video data D IMAT , corresponding to the compression result, in the recording medium  1009 . Also, the main controller  1007  respectively transmits the digital video data D IMAT , corresponding to the compression result, to the client terminals  904   a  to  904   m.    
         [0110]    Here, the main controller  1007  detects a current motion region ( 402  in  FIG. 4 ) from the digital video data D IMA   1  to D IMA (n) transferred from the ADC  201 , removes a high frequency component of a region ( 401  in  FIG. 4 ) except the detected current motion region  402 , and transmits the digital video data D IMAT  (which corresponds to the removal result) to the client terminals  904   a  to  904   m  (which are target devices) through the communication interface  1005  and the communication network  903 . In the present embodiment, the main controller  1007  performs the low pass filtering operation on video data of the region  401  except the current motion region  402 . 
         [0111]    Therefore, the high frequency component of the region  401  except the current motion region  402  is removed by the low pass filtering operation, and thus, the amount of data is reduced in a region unnecessary for surveillance. Accordingly, despite a large amount of data to be transmitted, video data effective for a user is transmitted to the client terminals  904   a  to  904   m  which are the target devices. 
         [0112]    For example, when digital video data obtained by removing a high frequency component of the region except the current motion region is additionally compressed and transmitted by the compressor  1008 , the relatively reduced amount of data is compressed, and thus, even when video data is compressed at a relatively low compression rate, the amount of compressed data may not relatively increase. Also, since a relatively low compression rate is applied, a current motion region necessary for surveillance becomes clearer. 
         [0113]      FIG. 11  illustrates an operation of the main controller  1007  of  FIG. 10 , according to an exemplary embodiment. Operations of  FIG. 11  may be separately performed for each of the digital video data D IMA   1  to D IMA (n) output from the ADC  1001 . This operation of the main controller  1007  will now be described with reference to  FIGS. 4 ,  5 ,  9 ,  10  and  11 . 
         [0114]    In operation S 1101 , the main controller  1007  detects a current motion region from the digital video data D IMA   1  to D IMA (n) output from the ADC  1001 . 
         [0115]    When the current motion region  402  is detected in operation S 1103 , the main controller  1007  performs the low pass filtering operation on video data of the region  401  except the current motion region  402  to remove the high frequency component therefrom, in operation S 1105 . 
         [0116]    In the present embodiment, the low pass filtering operation denotes an operation in which pixel values of the video data of the region  401  except the current motion region  402  are multiplied by a filter coefficient that is greater than a decimal number 0 and less than a decimal number 1. For example, the 3×3 mask  501  having a filter coefficient of 1/9 is used, and thus, the pixel values of the video data of the region  401  except the current motion region  402  are reduced by 1/9 times. 
         [0117]    Here, the filter coefficient increases in proportion to the number of previously-occurred motions in the region  401  except the current motion region  402 . For example, when the number of previously-occurred motions in the region  401  except the current motion region  402  is 14, the filter coefficient is 1/9, and when the number of previously-occurred motions in the region  401  except the current motion region  402  is 7, the filter coefficient is 1/18. Therefore, sharpness or resolution may be determined in proportion to an importance of the region  401  except the current motion region  402 . 
         [0118]    If the current motion region  402  is not detected in operation S 1103 , the main controller  1007  performs the low pass filtering operation on video data of all the regions  401  and  402  to remove the high frequency component therefrom in operation S 1107 . 
         [0119]    Subsequently, the main controller  1007  compresses digital video data, stores video data D IMAT  (corresponding to the compression result) in the recording medium  1009 , and transmits the video data D IMAT  to the client terminals  904   a  to  904   m  through the communication interface  1005 , in operation S 1109 . However, depending on the case, the digital video data may be stored and transmitted without being compressed. 
         [0120]    Operations S 1101  to S 1109  are periodically repeated until the end signal is generated in operation S 1111 . 
         [0121]      FIG. 12  illustrates an operation of the main controller  1007  of  FIG. 10 , according to another exemplary embodiment. Operations of  FIG. 12  may be separately performed for each of the digital video data D IMA   1  to D IMA (n) output from the ADC  1001 . This operation of the main controller  1007  will now be described with reference to  FIGS. 4 ,  5 ,  9 ,  10  and  12 . 
         [0122]    In operation S 1201 , the main controller  1007  detects a current motion region from the digital video data D IMA   1  to D IMA (n) output from the ADC  1001 . 
         [0123]    If the current motion region  402  is not detected in operation S 1203 , the main controller  1007  performs the low pass filtering operation on video data of all the regions  401  and  402  to remove the high frequency component therefrom in operation S 1209 . 
         [0124]    If the current motion region  402  is detected in operation S 1203 , the main controller  1007  determines whether the predetermined target  402   a  is detected from the current motion region  402 , in operation S 1205 . 
         [0125]    Here, kinds of the predetermined target  402   a  are various depending on the surveillance purpose of the surveillance system. That is, regarding the advance of motion detection technology including object classification technology, the predetermined target  402   a  may be a person, an animal, or a vehicle which moves in a specific manner, may be a person or an animal which has a specific shape and color, or may be a specific object. 
         [0126]    However, periodically-moving objects (for example, a tree shaken by wind, a rotating electric fan, an ascending/descending elevator, etc.) may be set as a non-moving target. 
         [0127]    If the predetermined target  402   a  is not detected in operation S 1205 , the main controller  1007  performs the low pass filtering operation on the video data of all the regions  401  and  402  to remove the high frequency component therefrom, in operation S 1209 . 
         [0128]    If the predetermined target  402   a  is detected in operation S 1205 , the main controller  1007  performs the low pass filtering operation on the video data of the region  401  except the current motion region  402  to remove the high frequency component in operation S 1207 . 
         [0129]    Subsequently, the main controller  1007  compresses digital video data, stores video data D IMAT  (corresponding to the compression result) in the recording medium  1009 , and transmits the video data D IMAT  to the client terminals  904   a  to  904   m  through the communication interface  1005 , in operation S 1211 . However, depending on the case, the digital video data may be stored and transmitted without being compressed. 
         [0130]    Operations S 1201  to S 1211  are periodically repeated until the end signal is generated in operation S 1213 . 
         [0131]      FIG. 13  illustrates an operation of the main controller  1007  of  FIG. 10 , according to still another exemplary embodiment. Operations of  FIG. 13  may be separately performed for the digital video data D IMA   1  to D IMA (n) output from the ADC  1001 . This operation of the main controller  1007  will now be described with reference to  FIGS. 4 ,  5 ,  9 ,  10  and  13 . 
         [0132]    In operation S 1301 , the main controller  1007  detects a current motion region from the digital video data D IMA   1  to D IMA (n) output from the ADC  1001 . 
         [0133]    If the current motion region  402  is not detected in operation S 1303 , the main controller  1007  performs the low pass filtering operation on video data of all the regions  401  and  402  to remove the high frequency component therefrom, in operation S 1309 . Also, the main controller  1007  compresses digital video data of all the regions  401  and  402 , stores video data D IMAT  (corresponding to the compression result) in the recording medium  1009 , and transmits the video data D IMAT  to the client terminals  904   a  to  904   m  through the communication interface  1005 , in operation S 1311 . 
         [0134]    If the current motion region  402  is detected in operation S 1303 , the main controller  1007  performs the low pass filtering operation on video data of the region  401  except the current motion region  402  to remove the high frequency component therefrom, in operation S 1305 . Also, the main controller  1007  compresses digital video data of the region  401  except the current motion region  402 , stores video data D IMAT  (corresponding to the compression result) in the recording medium  1009 , and transmits the video data D IMAT  to the client terminals  904   a  to  904   m  through the communication interface  1005 , in operation S 1307 . 
         [0135]    Operations S 1301  to S 1311  are periodically repeated until the end signal is generated in operation S 1313 . 
         [0136]      FIG. 14  illustrates an internal configuration of the main controller  1007  of  FIG. 10 , according to an exemplary embodiment. The internal configuration of the main controller  1007  will now be described in detail with reference to  FIGS. 10 and 14 . 
         [0137]    The main controller  1007  includes a motion detector  1401 , a low pass filter (LPF)  1403 , a compression setter  1405 , and a core processor  1407 . 
         [0138]    The motion detector  1401  detects a current motion region from the digital video data D IMA   1  to D IMA (n) output from the ADC  1001 . 
         [0139]    The LPF  1403  filters out the high frequency component of a region except a current motion region in the digital video data D IMA   1  to D IMA (n) output from the ADC  1001 , according to information about the current motion region received from the motion detector  1401 , and supplies digital video data, corresponding to the removal result, to the compressor  1008  as a compression target. 
         [0140]    The compression setter  1405  generates information about a compression exclusion region according to the information about the current motion region from the motion detector  1401 , and supplies the information about the compression exclusion region, corresponding to the generation result, to the compressor  1008 . 
         [0141]    The core processor  1407  controls operations of the motion detector  1401 , the LPF  1403 , and the compression setter  1405 , and outputs the video data D IMAT  (corresponding to the compression result), output from the compressor  1008 , to the communication interface  1005  and the recording medium  1009 . 
         [0142]    As described above, according to the above embodiments, in the surveillance camera and the digital video recorder, a current motion region is detected from digital video data, a high frequency component of a region except the detected current motion region is removed, and digital video data corresponding to the removal result is transmitted to a target device over a communication network. 
         [0143]    Therefore, the high frequency component of the region except the current motion region is removed by a low pass filtering operation, and thus, the amount of data is reduced in a region unnecessary for surveillance. Accordingly, despite a large amount of data to be transmitted, video data effective for a user is transmitted to a target device. 
         [0144]    For example, when digital video data obtained by removing a high frequency component is additionally compressed and transmitted, the relatively reduced amount of data is compressed, and thus, even when video data is compressed at a relatively low compression rate, the amount of compressed data may not relatively increase. Also, since a relatively low compression rate is applied, a current motion region necessary for surveillance becomes clearer. 
         [0145]    It should be understood that the above exemplary embodiments should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other exemplary embodiments. 
         [0146]    While various exemplary embodiments have been described with reference to the drawings, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the inventive concept as defined by the following claims.