Patent Publication Number: US-10785531-B2

Title: Video synopsis method and related video synopsis device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a video synopsis method and a related video synopsis device, and more particularly, to a video synopsis method for overlapping videos generated in different periods and a related video synopsis device. 
     2. Description of the Prior Art 
     A monitoring apparatus applied to a public road or a storehouse has to continuously record a video about a monitoring region for preventing missing any abnormal event. The time length of the monitoring video may have hundreds of hours; when the abnormal event happened, the user has a high speed playback of the monitoring video in order to check the monitoring video in a short time. A drawback of the high speed playback is that an object inside the frame moves fast, so that the user may miss a clue in response to failure of mind. The user cannot browse the high speed playback for a long time, and has to take a rest periodically therefore investigation efficiency is decreased accordingly. Design of a video analyzing method capable of condensing the time length of the monitoring video and showing all frames of the monitoring video in a short time period is an important issue in the related monitoring industry. 
     SUMMARY OF THE INVENTION 
     The present invention provides a video synopsis method for overlapping videos generated in different time periods and a related video synopsis device for solving above drawbacks. 
     According to the claimed invention, a video synopsis method for overlapping videos generated in different periods includes dividing a monitoring film into a plurality of videos, acquiring a pixel difference between frames respectively from the plurality of videos at the same time sequence of each video, acquiring a weighting parameter according to the pixel difference, and utilizing the weighting parameter to overlap the frames respectively from different videos so as to generate a composite result. 
     According to the claimed invention, a video synopsis device with a function of overlapping videos generated in different periods includes an video receiver and an operation processor. The video receiver is adapted to receive a monitoring film. The operation processor is electrically connected to the video receiver. The operation processor is adapted to divide a monitoring film into a plurality of videos, acquire a pixel difference between frames respectively from the plurality of videos at the same time sequence of each video, acquire a weighting parameter according to the pixel difference, and utilize the weighting parameter to overlap the frames respectively from different videos so as to generate a composite result, for condensing the plurality of videos of the monitoring film into a composite video. 
     The video synopsis method and the related video synopsis device of the present invention can condense the long-term monitoring film into the short-term composite video. The object within the frames can be overlapped via the mask acquired by the video tracking technology or the weighting acquired by the video difference generated in different periods for composition process. Each composite frame of the composite video can simultaneously show several patterns of the object within the frames of the monitoring film captured in different periods, so as to increase investigation efficiency when having a playback of the monitoring film. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a functional block diagram of a video synopsis device according to an embodiment of the present invention. 
         FIG. 2  is a flow chart of a video synopsis method according to the embodiment of the present invention. 
         FIG. 3  is a diagram of the monitoring film according to the embodiment of the present invention. 
         FIG. 4  is a diagram of video frames generated in different period according to the embodiment of the present invention. 
         FIG. 5  is a flow chart of the video synopsis method according to another embodiment of the present invention. 
         FIG. 6  is a diagram of the video frames generated in different periods according to another embodiment of the present invention. 
         FIG. 7  is a diagram of a composition about the series of frames according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 1  and  FIG. 2 .  FIG. 1  is a functional block diagram of a video synopsis device  10  according to an embodiment of the present invention.  FIG. 2  is a flow chart of a video synopsis method according to the embodiment of the present invention. The video synopsis method illustrated in  FIG. 2  can be suitable for the video synopsis device  10  shown in  FIG. 1 . The video synopsis device  10  can include a video receiver  12  and an operation processor  14  electrically connected to each other. The video receiver  12  can be used to receive a monitoring film. The operation processor  14  can execute the video synopsis method according to the monitoring film, such as condensing a plurality of videos within the monitoring film into a composite video. In the present invention, the video synopsis method can divide the monitoring film into several videos in time order, and overlap the foresaid videos generated in different periods, so that the user can quickly browse the monitoring film. 
     Please refer to  FIG. 2  to  FIG. 4 .  FIG. 3  is a diagram of the monitoring film according to the embodiment of the present invention.  FIG. 4  is a diagram of video frames generated in different period according to the embodiment of the present invention. In respect of the video synopsis method, step S 200  can be executed to divide the monitoring film into the plurality of videos by the operation processor  14 , and the plurality of videos can be videos V 1 , V 2 , V 3  and V 4 . The monitoring film preferably can be divided into at least three videos. In this embodiment, the monitoring film is divided into four videos, and certainly an amount of the videos depends on an actual demand. All the video has the same time length. Then, steps  5202  and S 204  can be executed that the operation processor  14  acquires at least one pixel difference between frames F 1 , F 2 , F 3  and F 4  respectively from the videos V 1 , V 2 , V 3  and V 4  at the same time sequence of each video, and acquires weighting parameters in accordance with the pixel difference between the foresaid frames. 
     In the embodiment, the weighting parameter can be a mask generated by the pixel difference result. The weighting parameter can be computed by an external computer device or the video synopsis device  10 . The mask can be used to indicate whether an object is in the frame. For example, a pixel of the mask which corresponds to the object within the frame can have a first weighting, and a pixel of the mask which does not correspond to the object within the frame can have a second weighting. The first weighting can be equal to 1 and the second weighting can be equal to 0. As shown in  FIG. 4 , the frames F 1  and F 4  do not have the object (such as a human being), so that all pixels of the masks M 1  and M 4  can have the second weighting (which is shown by a slash area); the frames F 2  and F 3  have the object, so that pixels of the masks M 2  and M 3  corresponding to the object within the frames F 2  and F 3  can have the first weighting (which is shown by a space area) and other pixels not corresponding to the object can have the second weighting. 
     For a start, the monitoring film can be divided into n number of videos. A symbol I k  can be represented as a pixel within the k-th video related to a timing t and coordinates (x, y), such as the formula 1. A computation symbol of the mask M can be represented by a k , such as the formula 2, and used to indicate the weighting within the k-th video related to the timing t and the coordinates (x, y). Parameters k and n are positive integers. Steps S 206 , S 208  and S 210  can be executed that the operation processor  14  acquires a weighting sum a of all weightings inside the mask via the formula 3 and the weighting sum a is not smaller than 1, and computes a product sum of the frames F 1 , F 2 , F 3  and F 4  respectively multiplied by corresponding weighting of the masks M 1 , M 2 , M 3  and M 4  via the formula 4, and computes a ratio of the product sum to the weighting sum a for acquiring a composite result S. It should be mentioned that the symbol I k  can belong to a pixel of a specific frame within the k-th video, and the composite result S can be generated by utilizing the mask to overlap pixels on specific positions of the corresponding frames from every video in time order, which means the video synopsis device  10  can composite pixels on all positions of the frames and then the composite frame Fc and the composite video (which is not shown in figures) including the plurality of videos can be generated. 
     
       
         
           
             
               
                 
                   
                     
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     For example, the monitoring film of the prevent invention may have sixty minutes, and each of the four videos may be equal to fifteen minutes. For example, the video V 1  can include fifteen minutes from 00:00 to 14:59, and the video V 2  can include fifteen minutes from 15:00-29:59, and the video V 3  can include fifteen minutes from 30:00-44:59, and the video V 4  can include fifteen minutes from 45:00-59:59. The corresponding frame from every video in time order can be the frame F 1  at a time 00:00, the frame F 2  at a time 15:00, the frame F 3  at a time 30:00, and the frame F 4  at a time 45:00, which means the frames are captured at the same time sequence within the corresponding video. Each pixel of the frame F 1  can be overlapped with the corresponding pixels of the frames F 2 , F 3  and F 4  via the formula 3 and the formula 4 to acquire the composite result S, and a plurality of composite results S can be acquired and have an amount the same as the pixel number of the frame. The plurality of composite results S can be used to generate the composite frame Fc and the composite video. 
     As shown in  FIG. 4 , the frame F 2  has a passerby wearing pants, and the frame F 3  has a passerby wearing a skirt, and the frames F 1  and F 4  have no passerby. The video synopsis method of the present invention can merge the frames F 1 , F 2 , F 3  and F 4  to generate the composite frame Fc having a pattern of the passerby wearing the pants overlapped with the passerby wearing the skirt, and a time length of the composite video has fifteen minutes. An effect of the composite frame Fc may be varied in accordance with parameters of the mask. For example, if a range of the first weighting inside the mask M 3  does not match a dimension of the object, such as the passerby wearing the skirt, an upper body of the passerby wearing the skirt inside the frame Fc will be filtered. The range of the first weighting inside the mask M 3  can be enlarged to cover all pixels of the passerby wearing the skirt for overcoming the above-mentioned situation, and a detailed description about adjusting the weighting range is omitted herein for simplicity. In addition, the video synopsis method may optionally blur the mask after execution of step S 204 . The blurred mask can be used to overlap the corresponding frames from the videos generated in different periods for effectively smoothing a contour of the object within the composite result S, the composite frame Fc and the composite video, which means the overlapping pattern (the passerby wearing the pants and the passerby wearing the skirt) and background can be merged in a color gradient manner. 
     Please refer to  FIG. 3 , and  FIG. 5  to  FIG. 6 .  FIG. 5  is a flow chart of the video synopsis method according to another embodiment of the present invention.  FIG. 6  is a diagram of the video frames generated in different periods according to another embodiment of the present invention. The video synopsis method illustrated in  FIG. 5  is suitable for the video synopsis device  10  shown in  FIG. 1 . First, steps S 500 , S 502  and S 504  can be executed that the operation processor  14  divides the monitoring film into the plurality of videos V 1 , V 2 , V 3  and V 4 , and acquires the pixel difference between the frames F 1 , F 2 , F 3  and F 4  respectively from the videos V 1 , V 2 , V 3  and V 4  in time order, and acquires the weighting parameters via the pixel difference between different frames. In this embodiment, the pixel difference can be a video difference d k  between each video and other videos within the plurality of videos via the formula 5, and a difference value d k ′ between the video difference d k  of each video and a minimal video difference about other videos can be acquired via the formula 6, and the difference value d k ′ can be optionally transformed into the weighting parameter w k  via normalization process as the formula 7. Parameters p and q can be arbitrary numbers. Parameters k, n and j can be positive integers. 
     Generally, the difference value d k ′ computed by the formula 6 can be the weighting parameter, however the present invention can further plus the difference value d k ′ and an adjusting value ε (which is a minimum but not zero) to prevent a sum of the weighting parameter about the n number of videos from being zero, as mentioned by the formula 7. Then, the video synopsis method can execute steps S 506  and S 508  to compute the product sum of the frames respectively from different videos multiplied by the corresponding weighting parameters, and then compute the ratio of the product sum to the sum of the weighting parameters of the plurality of videos for acquiring the composite result S. As the embodiment mentioned above, the composite result S is merged by specific pixels respectively from the frames F 1 , F 2 , F 3  and F 4 , and the video synopsis method can acquire the plurality of composite results S about all pixels within the frame for generating the composite frame Fc and the composite video. 
     
       
         
           
             
               
                 
                   
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     The video synopsis method of the present invention not only can overlap the plurality of videos generated in different time periods, but also can merge a series of frames acquired by motion detection into the single composite frame. Please refer to  FIG. 3 ,  FIG. 4  and  FIG. 7   FIG. 7  is a diagram of a composition about the series of frames according to another embodiment of the present invention. As shown in  FIG. 4 , the video V 2  captures the passerby wearing the pants walks inside the monitoring region, and the first frame F 2 , the second frame F 2 ′ and the third frame F 2 ″ can be the series of frames captured at different timing and respectively record steps of a moving trace about the passerby wearing the pants. The video synopsis method of the present invention can utilize the weighting parameter acquired by the mask or the video difference of the above-mentioned embodiments to overlap the frames F 2 , F 2 ′ and F 2 ″ for generating the composite frame. As shown in  FIG. 7 , the single composite frame Fc′ can show the passerby wearing the pants walks from left to right. 
     In conclusion, the video synopsis method and the related video synopsis device of the present invention can condense the long-term monitoring film into the short-term composite video. The object within the frames can be overlapped via the mask acquired by the video tracking technology or the weighting acquired by the video difference generated in different periods for composition process. Each composite frame of the composite video can simultaneously show several patterns of the object within the frames of the monitoring film captured in different periods, so as to increase investigation efficiency when having a playback of the monitoring film. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.