Patent Publication Number: US-2006008245-A1

Title: Image processing device and method

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims priority from Korean Patent Application No. 10-2004-0053086 filed on Jul. 8, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an image processing device and method, and more particularly, to an image processing device and method which can restore a loss caused during compression and storage of a video frame.  
      2. Description of Related Art  
      Digital video recorders (DVR) are generally used to monitor indoor and outdoor environments of buildings, underground parking lots, bank windows, or unmanned banking terminals.  
      DVRs store video/audio data in storage media such as hard disk drives or optical discs such as compact disc-recordables (CD-R), CD-rewritables (CD-RW), and digital versatile disc-recordables (DVD-R).  
      A DVR is connected to at least one camera and sensor that can acquire video data, and a user controls the operation of the camera and sensor using the DVR.  
      As shown in  FIG. 1 , a conventional image processing device includes a converting unit  10  that converts a video frame into a digital signal, a compressing unit  20  that compresses the converted video frame using a specified compression compressor/decompressor (codec), a video storing unit  30  that stores the compressed video frame, a reproducing unit  40  that extracts a video frame from the video storing unit  30  and reproduces the extracted video frame, and a decompressing unit  50  that decompresses the video frame extracted from the video storing unit  30  and transmits the decompressed video frame to the reproducing unit  40 .  
      The converting unit  10  converts video frames transmitted from an additional data processing unit  70 , which adds specified data to vertical blank interval (VBI) of video frames transmitted from a plurality of video acquiring units  61 ,  62 , and  63 , each of which acquires a video frame at a specified position.  
      The additional data processing unit  70  displays the frame transmitted from the reproducing unit  40  on a display unit  80 .  
      The VBI is a portion of a video that is not displayed on the display unit  80 . The VBI includes additional data such as caption information, time information, and information about a video acquiring unit that transmits a corresponding video frame.  
      To efficiently use the video storing unit  30  having a limited storage space, the compressing unit  20  compresses the converted video frame after removing from the converted video frame a high-frequency area that is difficult for a viewer to recognize.  
      At this time, when the converted video frame is compressed by the compressing unit  20 , a high-frequency area of additional data included in a VBI of the converted video frame is also removed.  
      The reproducing unit  40  extracts a video frame to be reproduced from the video storing unit  30  and the decompressing unit  50  decompresses the extracted video frame and transmits the decompressed video frame to the reproducing unit  40 .  
      The additional data processing unit  70  displays a video frame transmitted from the reproducing unit  40  on the display unit  80 .  
      The conventional image processing device operates as follows.  
      Referring to  FIGS. 1 and 2 , a video frame acquired at a specified position is transmitted from each of the plurality of video acquiring units  61 ,  62 , and  63  to the converting unit  10  through the additional data processing unit  70  in operation S 11 .  
      At this time, the additional data processing unit  70  transmits the video frame received from each of the plurality of video acquiring units  61 ,  62 , and  63  to the converting unit  10  after adding additional data to a VBI of the received video frame.  
      The converting unit  10  converts the transmitted video frame into a digital signal in operation S 12  and the compressing unit  20  compresses the converted video frame using a specified compression codec in operation S 13 .  
      The compressed video frame is stored in the video storing unit  30  in operation S 14 .  
       FIG. 3  is a flowchart illustrating a conventional method for reproducing a video frame stored in the video storing unit  30 .  
      Referring to  FIGS. 1 and 3 , in operation S 21 , the reproducing unit  40  extracts a video frame to be reproduced from the video storing unit  30 .  
      The extracted video frame is decompressed by the decompressing unit  50  in operation S 22  and the reproducing unit  40  transmits the decompressed video frame to the additional data processing unit  70  in operation S 23 .  
      The additional data processing unit  70  displays the transmitted video frame in various ways according to additional data included in a VBI of the transmitted video frame in operation S 24 .  
      For example, the additional data processing unit  70  divides a screen of the display unit  80  into a number of sections corresponding to the number of video acquiring units that acquire video frames.  
      However, in the conventional image processing device and method, the compressing unit  20  compresses a video frame after removing a high-frequency area of the video frame for efficient use of the storage space of the video storing unit  30 .  
      Thus, when a video frame stored in the video storing unit  30  is reproduced, the video frame transmitted from each of the plurality of video acquiring units  61 ,  62 , and  63  is different from the video frame reproduced by the reproducing unit  40 , since the high-frequency area is removed from the additional data.  
      Thus, when the additional data processing unit  70  displays the video frame transmitted from the reproducing unit  40  on the display unit  80 , it is difficult for the display unit  80  to display the video frame using a proper display method due to loss of the additional data included in the VBI of the video frame.  
      Korean Patent Publication No. 1994-0010514 discloses a system for determining a malfunction of a frame memory by inserting a frame operation determining signal in a VBI of a video signal and detecting the frame operation determining signal of the video signal in a current frame and the frame operation determining signal of the video signal in an immediately previous frame. The system involves self-diagnosing the malfunction of the frame memory by detecting the frame operation determining signal of a video signal in a current frame and the frame operation determining signal of the video signal in an immediately previous frame, but does not suggest a method for restoring a loss caused by the malfunction of the frame memory.  
     BRIEF SUMMARY  
      An aspect of the present invention provides an image processing device and method which can restore losses in additional data included in a VBI of a video frame by detecting a pattern of the additional data.  
      According to an aspect of the present invention, there is provided an image processing device including a pattern detecting unit, a video storing unit, and a pattern storing unit. The pattern detecting unit detects a pattern of additional data included in a vertical blank interval (VBI) of a video frame. The video storing unit stores the video frame. The pattern restoring unit restores the additional data based on the detected pattern when the stored video frame is reproduced.  
      According to another aspect of the present invention, there is provided an image processing method including detecting a pattern of additional data included in a vertical blank interval (VBI) of a specified video frame, storing the specified video frame, and restoring the additional data using the detected pattern when the stored video frame is reproduced.  
      According to another aspect of the present invention, there is provided an image processing method, including: adding additional information to a video frame; detecting a pattern of the additional data; compressing the video frame by removing a high frequency area of the additional data; and decompressing the compressed video frame and restoring the additional information using the detected pattern.  
      According to another aspect of the present invention, there is provided a method of increasing video frame storing efficiency, including: detecting a pattern of additional data included in a video frame, the pattern being usable to restore the additional data when the video frame is reproduced from a storage; compressing the video frame by removing a high frequency area of the additional data; and storing the video frame in the storage.  
      According to another aspect of the present invention, there is provided a method of increasing video frame reproducing efficiency, including: extracting a compressed stored video frame; and decompressing the extracted video frame and restoring lost additional data to the video frame using a detected pattern of the additional data, the detected pattern being detected in the video frame before compression of the video frame.  
      Additional and/or other aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following detailed description, taken in conjunction with the accompanying drawings of which:  
       FIG. 1  illustrates a conventional image processing device;  
       FIG. 2  is a flowchart illustrating a conventional method for storing a video frame;  
       FIG. 3  is a flowchart illustrating a conventional method for reproducing a video frame stored in a video storing unit;  
       FIG. 4  illustrates an image processing device according to an embodiment of the present invention;  
       FIG. 5  is a flowchart illustrating a method for storing a video frame according to an embodiment of the present invention;  
       FIG. 6  illustrates a pattern of additional data usable in an apparatus and method according to an embodiment of the present invention;  
       FIG. 7  illustrates a pattern of additional data which additional data regarded as noise is removed;  
       FIG. 8  is a flowchart illustrating a method for reproducing a video frame stored in a video storing unit;  
       FIG. 9  illustrates a pattern of additional data of a decompressed video frame; and  
       FIG. 10  illustrates a pattern of additional data that is restored based on a detected pattern.  
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
      Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
      As shown in  FIG. 4 , an image processing device according to an embodiment of the present invention includes a pattern detecting unit  111  that detects a pattern of additional data included in a vertical blank interval (VBI) of a specified video frame, a video storing unit  112  that stores the video frame, and a pattern restoring unit  113  that restores additional data based on the detected pattern.  
      The image processing device also includes a converting unit  114  that converts a video frame to be stored in the video storing unit  112  into a digital signal, a compressing unit  115  that compresses the video frame converted into the digital signal using a specified compression codec, a reproducing unit  116  that extracts a video frame from the video storing unit  112  and reproduces the extracted video frame, a decompressing unit  117  that decompresses the compressed video frame, and a memory unit  118  that stores a pattern of additional data that is detected by the pattern detecting unit  111 .  
      The video frame is acquired by each of a plurality of video acquiring units  121 ,  122 , and  123 , which are, by way of a non-limiting example, cameras, and the additional data processing unit  131  transmits the acquired video frame to the converting unit  114  after adding additional data to a VBI of the acquired video frame.  
      When video frames are simultaneously acquired from the plurality of video acquiring units  121 ,  122 , and  123 , the additional data processing unit  131  may add additional data such as, by way of a non-limiting example, information about the video acquiring units  121 ,  122 , and  123  and time information to VBIs of the respective video frames.  
      The additional data processing unit  131  generally transmits the video frames to the converting unit  114 . A speed of transmission can be  30  frames per second.  
      In this case, if the video frames are simultaneously transmitted from the plurality of video acquiring units  121 ,  122 , and  123  to the additional data processing unit  131 , they may be sequentially transmitted by the additional data processing unit  131  to the converting unit  114  in a specified order.  
      The additional data processing unit  131  adds to a VBI of the video frame additional data such as, by way of a non-limiting example, information about a video acquiring unit that transmits the video frame and time information about a time point at which the video frame is acquired.  
      The additional data processing unit  131  sends the video frames acquired by each of the plurality of video acquiring units  121 ,  122 , and  123  and a video frame reproduced by the reproducing unit  116  to a display unit  141  for display thereon.  
      When the video frame stored in the video storing unit  112  is reproduced, if video frames are simultaneously acquired from the plurality of video acquiring units  121 ,  122 , and  123 , the additional data processing unit  131  may divide a screen of the display unit  141  into several sections and display the acquired video frames on the divided sections of the screen, respectively.  
      The pattern detecting unit  111  can detect a pattern of additional data included in a VBI of the video frame converted into a digital signal before the video frame is compressed by the compressing unit  115 .  
      The pattern detecting unit  111  can detect a line of the VBI in which additional data exists and then detect a pattern of additional data that exist at specified intervals in the detected line.  
      Since lines with additional data may correspond to a number of pixels of the video frame, a section in which additional data exists and a specified interval between additional data may be distinguished from each other based on the number of pixels.  
      The pattern detecting unit  111  regards only additional data that exist at intervals of a specified number of pixels as an effective pattern of additional data and regards other additional data as noise and neglects such additional data. For example, when the intervals are 10 pixels, additional data that exist at intervals of 10 pixels are regarded as being valid and other additional data are regarded as noise and then neglected.  
      Since additional data added by an additional data processing unit exists at specified intervals, a video frame stored in the video storing unit  112  may only be displayed by the corresponding additional data processing unit.  
      Thus, when various additional data processing units are used, only a video frame to which additional data is added by an additional data processing unit can be displayed by the corresponding data processing unit.  
      To efficiently use the video storing unit  112 , the compressing unit  115  may compress the video frame converted into a digital signal using a compression codec like JPEG or MPEG.  
      The compressing unit  115  may reduce a space of the video storing unit  112  occupied by the video frame by removing a high-frequency area that is difficult for a viewer to recognize.  
      As a result, a loss may also occur in additional data included in a VBI of a video frame stored in the video storing unit  112 . The pattern restoring unit  113  may restore a loss in additional data when the video frame stored in the video storing unit  112  is reproduced.  
      At this time, the reproduction of the video frame stored in the video storing unit  112  may be made by extracting a video frame to be reproduced from the video storing unit  112 , decompressing the video frame in the decompressing unit  117 , and transmitting the decompressed video frame to the additional data processing unit  131 .  
      The pattern restoring unit  113  can restore additional data lost from a VBI of the decompressed video frame using a pattern of additional data of an uncompressed video frame that is detected by the pattern detecting unit  111 .  
      Thus, the additional data processing unit  131  can cause a video frame to be displayed on a specified display unit based on the restored additional data.  
      For example, when video frames are simultaneously acquired by a plurality of video acquiring units, the additional data processing unit  131  may divide a screen of the display unit  141  into a number of sections corresponding to the number of video acquiring units and display the video frames on the divided sections, respectively, based on additional data included in the video frames, such as information about the video acquiring units  121 ,  122 , and  123  and time information about time points at which the video frames are acquired.  
      An operation of the image processing device according an embodiment of the present invention is as follows.  
      An image processing method according to an embodiment of the present invention may be divided into a method for storing a video frame acquired by each of a plurality of video acquiring units and a method for reproducing a video frame stored in the video storing unit. These methods can be performed by the apparatus of  FIG. 4  and are, for ease of explanation only, described in conjunction with  FIG. 4 . However, it is to be understood that these methods can be performed by apparatuses of other configurations.  
      Referring to  FIGS. 4 and 5 , in a method for storing a video frame acquired by each of the plurality of video acquiring units  121 ,  122 , and  123 , the additional data processing unit  131  transmits a video frame acquired at a specified position from each of the plurality of video acquiring units  121 ,  122 , and  123  to the converting unit  114  in operation S 111 .  
      At this time, additional information such as information about a video acquiring unit that acquires the video frame and time information about a time point at which the video frame is acquired may be added by the additional data processing unit  131  to a VBI of the video frame transmitted to the converting unit  114 .  
      The converting unit  114  converts the video frame to which the additional data is added into a digital signal in operation S 112 . The video frame converted into the digital signal is compressed by the compressing unit  115  using a specified compression codec in operation S 113  and the compressed video frame is stored in the video storing unit  112  in operation S 114 .  
      A pattern of the additional data included in the VBI of the video frame converted into the digital signal is detected by the pattern detecting unit  111  in operation S 115  and the detected pattern is stored in the memory unit  118  in operation S 116 .  
      As shown in  FIG. 6 , the pattern of the additional data included in the VBI of the video frame converted into the digital signal may be detected using a section in which the additional data exists and a specified interval between additional data in a line in which additional data exist.  
      For example, if the specified interval between additional data is a pixel A, the pattern detecting unit  111  regards only additional data  151 ,  152 ,  153 , and  154  that exist at intervals of the pixel A as being valid and regards other additional data  155  and  156  as noise and neglects the additional data  155  and  156 . After removing the neglected additional data  155  and  156 , as shown in  FIG. 7 , a pattern of only pixels corresponding to sections in which the valid additional data  151 ,  152 , and  153 , and  154  exist can be detected.  
      Referring to  FIGS. 4 and 8 , in a method for reproducing a video frame stored in the video storing unit  112  according to another embodiment of the present invention, a video frame to be reproduced by the reproducing unit  116  is extracted from the video storing unit  112  in operation S 211 .  
      The extracted video frame is decompressed by the decompressing unit  117  in operation S 212 . At this time, as shown in  FIG. 9 , additional data  161 ,  162 ,  163 , and  164  included in a VBI of the decompressed video frame have losses when compared to a pattern of additional data before it is compressed, since high-frequency areas, e.g., edges of a pattern, are removed when the video frame is compressed by the compressing unit  115 . At this time, the pattern restoring unit  113  restores the losses in the decompressed video frame using the pattern stored in the memory unit  118  in operation S 213 .  
      Thus, as shown in  FIG. 10 , the losses occurring when compressing the video frame that is stored in the video storing unit  112  are restored to original additional data  171 ,  172 ,  173 , and  174  by the pattern restoring unit  113  using the pattern stored in the memory unit  118 . As shown in  FIG. 9 , the number of pixels in a section having decompressed additional data is compared to the number of pixels of additional data as shown in  FIG. 7 , and if the two numbers are the same, the decompressed additional data as shown in  FIG. 9  is restored using the detected pattern as shown in  FIG. 7 .  
      Once the additional data is restored by the pattern restoring unit  113 , the reproducing unit  116  transmits the decompressed video frame to the additional processing unit  131  in operation S 214 .  
      The additional data processing unit  131  displays the received video frame on the display unit  141  in various ways using additional data included in a VBI of the received video frame in operation S 215 . For example, when video frames are simultaneously acquired by the plurality of video acquiring units  161 ,  162 , and  163 , each video frame may include information about a corresponding video acquiring unit that acquires a corresponding video frame.  
      Thus, the additional data processing unit  131  may divide a screen of the display unit  141  into several sections and display the video frames acquired by the video acquiring units  161 ,  162 , and  163  on the respective divided sections based on the information about the video acquiring units  161 ,  162 , and  163 .  
      The image processing device and method according to the above-described embodiments of the present invention detect a pattern of additional data included in a VBI of a video frame and restores lost additional data using the detected pattern, thereby easily restoring additional data when loss compression is performed to improve the efficiency in storing a video frame.  
      Although a few embodiments of the present invention have been shown and described, the present invention is not limited to the described embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.